Silicon-containing film-forming composition, silicon-containing film, silicon-containing film-bearing substrate, and patterning method

ABSTRACT

A silicon-containing film is formed from a heat curable composition comprising (A) a silicon-containing compound obtained through hydrolytic condensation of a hydrolyzable silicon compound in the presence of an acid catalyst, (B) a hydroxide or organic acid salt of Li, Na, K, Rb or Ce, or a sulfonium, iodonium or ammonium compound, (C) an organic acid, (D) a cyclic ether-substituted alcohol, and (E) an organic solvent. The silicon-containing film ensures effective pattern formation, effective transfer of a photoresist pattern, and accurate processing of a substrate.

CROSS-REFERENCE TO RELATED APPLICATION

This non-provisional application claims priority under 35 U.S.C. §119(a)on Patent Application Nos. 2007-175956 and 2007-245832 filed in Japan onJul. 4, 2007 and Sep. 21, 2007, respectively, the entire contents ofwhich are hereby incorporated by reference.

TECHNICAL FIELD

This invention relates to a silicon-containing film-forming compositionsuitable for forming a silicon-containing film for use as anintermediate layer in a multilayer resist process which is used inmicropatterning in the manufacturing process of semiconductor devicesand the like, especially for forming such a silicon-containing film byspin coating; a silicon-containing film formed therefrom; asilicon-containing film-bearing substrate; and a patterning method usingthe same.

BACKGROUND ART

In the drive for higher integration and operating speeds in LSI devices,the pattern feature size is made drastically finer. Under theminiaturizing trend, the lithography has achieved formation of finerpatterns by using a light source with a shorter wavelength and by achoice of a proper resist composition for the shorter wavelength.Predominant among others are positive photoresist compositions which areused as a single layer. These single-layer positive photoresistcompositions are based on resins possessing a framework havingresistance to dry etching with chlorine or fluorine gas plasma andprovided with a resist mechanism that exposed areas become dissolvable.Typically, the resist composition is coated on a substrate to beprocessed (referred to as “processable substrate,” hereinafter) andexposed to a pattern of light, after which the exposed areas of theresist coating are dissolved to form a pattern. Then, the substrate canbe processed by dry etching with the remaining resist pattern serving asan etching mask.

In an attempt to achieve a finer feature size, i.e., to reduce thepattern width with the thickness of a photoresist coating keptunchanged, the photoresist coating becomes low in resolutionperformance. If the photoresist coating is developed with a liquiddeveloper to form a pattern, the so-called “aspect ratio” (depth/width)of the resist pattern becomes too high, resulting in pattern collapse.For this reason, the miniaturization is accompanied by a thicknessreduction of the photoresist coating (thinner coating).

On the other hand, a method commonly used for the processing of aprocessable substrate is by processing a substrate by dry etching withthe patterned photoresist film made an etching mask. Since a dry etchingmethod capable of establishing a full etching selectivity between thephotoresist film and the processable substrate is not available inpractice, the resist film is also damaged during substrate processing.That is, the resist film breaks down during substrate processing,failing to transfer the resist pattern to the processable substratefaithfully. As the pattern feature size is reduced, resist materials arerequired to have higher resistance to dry etching.

With the progress of the exposure wavelength toward a shorterwavelength, the resin in resist compositions is required to have lesslight absorption at the exposure wavelength. In response to changes fromi-line to KrF and to ArF, the resin has made a transition to novolacresins, polyhydroxystyrene and aliphatic polycyclic skeleton resins.Actually, the etching rate under the above-indicated dry etchingconditions has been accelerated. Advanced photoresist compositionsfeaturing a high resolution tend to be rather low in etching resistance.This suggests the inevitableness that a processable substrate is dryetched through a thinner photoresist coating having weaker etchingresistance. It is urgently required to have the material and processsuited in this processing stage.

One solution to these problems is a multilayer resist process. Theprocess involves forming an intermediate film on a processablesubstrate, forming a photoresist film (resist overcoat film) thereon,wherein the intermediate film with different etching selectivity fromthe resist overcoat film intervenes between the resist overcoat film andthe processable substrate, patterning the resist overcoat film, dryetching the intermediate film through the overcoat resist pattern as anetching mask for thereby transferring the pattern to the intermediatefilm, and dry etching the processable substrate through the intermediatefilm pattern as an etching mask for thereby transferring the pattern tothe processable substrate.

Included in the multilayer resist process is a bi-layer resist process.One exemplary bilayer resist process uses a silicon-containing resin asthe overcoat resist material and a novolac resin as the intermediatefilm (e.g., JP-A 6-95385). The silicon resin exhibits good resistance toreactive dry etching with an oxygen plasma, but is readily etched awaywith a fluorine gas plasma. On the other hand, the novolac resin isreadily etched away by reactive dry etching with an oxygen gas plasma,but exhibits good resistance to dry etching with fluorine and chlorinegas plasmas. Thus, a novolac resin film is formed on a processablesubstrate as a resist intermediate film, and a silicon-containing resinis coated thereon as a resist overcoat film. Subsequently, thesilicon-containing resist film is patterned by exposure to energyradiation and post-treatments including development. While the patternedsilicon-containing resist film serves as an etching mask, reactive dryetching with an oxygen plasma is carried out for etching away a portionof the novolac resin where the resist pattern has been removed, therebytransferring the pattern to the novolac film. While the patterntransferred to the novolac film serves as an etching mask, theprocessable substrate is etched with a fluorine or chlorine gas plasmafor transferring the pattern to the processable substrate.

In the pattern transfer by dry etching, a transfer pattern having arelatively good profile is obtained if the etching mask has asatisfactory etching resistance. Since problems like pattern collapsecaused by such factors as friction by a developer during resistdevelopment are unlikely to occur, a pattern having a relatively highaspect ratio is produced. Therefore, even though a fine pattern couldnot be formed directly from a resist film of novolac resin having athickness corresponding to the thickness of an intermediate film becauseof pattern collapse during development due to the aspect ratio problem,the use of the bi-layer resist process enables to produce a fine patternof novolac resin having a sufficient thickness to serve as a mask fordry etching of the processable substrate.

Also included in the multilayer resist process is a tri-layer resistprocess which can use general resist compositions as used in thesingle-layer resist process. In the tri-layer resist process, forexample, an organic film of novolac resin or the like is formed on aprocessable substrate as a resist undercoat film, a silicon-containingfilm is formed thereon as a resist intermediate film, and an ordinaryorganic photoresist film is formed thereon as a resist overcoat film. Ondry etching with a fluorine gas plasma, the resist overcoat film oforganic nature provides a satisfactory etching selectivity ratiorelative to the silicon-containing resist intermediate film. Then, theresist pattern is transferred to the silicon-containing resistintermediate film by dry etching with a fluorine gas plasma. With thisprocess, even on use of a resist composition which is difficult to forma pattern having a sufficient thickness to allow for direct processingof a processable substrate, or a resist composition which hasinsufficient dry etching resistance to allow for substrate processing, apattern of novolac film having sufficient dry etching resistance toallow for substrate processing is obtainable like the bilayer resistprocess, as long as the pattern can be transferred to thesilicon-containing film.

The silicon-containing resist intermediate films used in the tri-layerresist process described above include silicon-containing inorganicfilms deposited by CVD, such as SiO₂ films (e.g., JP-A 7-183194) andSiON films (e.g., JP-A 7-181688); and films formed by spin coating, suchas spin-on-glass (SOG) films (e.g., JP-A 5-291208, J. Appl. Polym. Sci.,Vol. 88, 636-640 (2003)) and crosslinkable silsesguioxane films (e.g.,JP-A 2005-520354). Polysilane films (e.g., JP-A 11-60735) would also beuseful. Of these, the SiO₂ and SiON films have a good function as a dryetching mask during dry etching of an underlying organic film, butrequire a special equipment for their deposition. By contrast, the SOGfilms, crosslinkable silsesquioxane films and polysilane films arebelieved high in process efficiency because they can be formed simply byspin coating and heating.

The applicable range of the multilayer resist process is not restrictedto the attempt of increasing the maximum resolution of resist film. Forexample, in a via-first method which is one of substrate processingmethods where an intermediate substrate to be processed has large steps,an attempt to form a pattern with a single resist film encountersproblems like inaccurate focusing during resist exposure because of asubstantial difference in resist film thickness. In such a case, stepsare buried by a sacrificial film for flattening, after which a resistfilm is formed thereon and patterned. This situation entails inevitableuse of the multilayer resist process mentioned above (e.g., JP-A2004-349572).

While silicon-containing films are conventionally used in the multilayerresist process, they suffer from several problems. For example, as iswell known in the art, where an attempt is made to form a resist patternby photolithography, exposure light is reflected by the substrate andinterferes with the incident light, incurring the problem of so-calledstanding waves. To produce a microscopic pattern of a resist filmwithout edge roughness, an antireflective coating (ARC) must be providedas an intermediate layer. Reflection control is essential particularlyunder high-NA exposure conditions of the advanced lithography.

In the multilayer resist process, especially the process of forming asilicon-containing film as an intermediate layer by CVD, it becomesnecessary for reflection control purposes to provide an organicantireflective coating between the resist overcoat film and thesilicon-containing intermediate film. However, the provision of theorganic ARC entails the necessity that the organic ARC be patterned withthe resist overcoat film made a dry etching mask. That is, the organicARC is dry etched with the resist overcoat film made a dry etching mask,after which the process proceeds to processing of the silicon-containingintermediate layer. Then the overcoat photoresist must bear anadditional load of dry etching corresponding to the processing of theARC. While photoresist films used in the advanced lithography becomethinner, this dry etching load is not negligible. Therefore, greaterattention is paid to the tri-layer resist process in which alight-absorbing silicon-containing film not creating such an etchingload is applied as an intermediate film.

Known light-absorbing silicon-containing intermediate films includelight-absorbing silicon-containing films of spin coating type. Forexample, JP-A 2005-15779 discloses the provision of an aromaticstructure as the light-absorbing structure. Since the aromatic ringstructure capable of effective light absorption acts to reduce the rateof dry etching with a fluorine gas plasma, this approach isdisadvantageous for the purpose of dry etching the intermediate filmwithout an additional load to the photoresist film. Since it is thusundesirable to incorporate a large amount of such light-absorbingsubstituent groups, the amount of incorporation must be limited to theminimum.

Further, the dry etching rate of the resist undercoat film duringreactive dry etching with an oxygen gas plasma as commonly used in theprocessing of the resist undercoat film with the intermediate film madea dry etching mask is preferably low so as to increase the etchingselectivity ratio between the intermediate film and the undercoat film.To this end, the intermediate film is desired to have a higher contentof silicon which is highly reactive with fluorine etchant gas. Therequirement arising from the conditions of processing both the overcoator photoresist film and the undercoat or organic film gives preferenceto an intermediate film having a higher content of silicon which ishighly reactive with fluorine gas.

In actual silicon-containing intermediate film-forming compositions ofspin coating type, however, organic substituent groups are incorporatedinto the silicon-containing compounds so that the silicon-containingcompounds may be dissolvable in organic solvents. Of thesilicon-containing intermediate films known in the art, an SOGfilm-forming composition adapted for KrF excimer laser lithography isdisclosed in J. Appl. Polym. Sci., Vol. 88, 636-640 (2003). However,since light-absorbing groups are described nowhere, it is believed thatthis composition forms a silicon-containing film without anantireflective function. This film fails to hold down reflection duringexposure by the lithography using the advanced high-NA exposure system.It would be impossible to produce microscopic pattern features.

In addition to the dry etching properties and antireflection effect, thecomposition for forming an intermediate film with a high silicon contentsuffers from several problems, of which shelf stability is mostoutstanding. The shelf stability relates to the phenomenon that acomposition comprising a silicon-containing compound changes itsmolecular weight during shelf storage as a result of condensation ofsilanol groups on the silicon-containing compound. Such molecular weightchanges show up as film thickness variations and lithography performancevariations. In particular, the lithography performance is sensitive, andso, even when the condensation of silanol groups within the moleculetakes place merely to such an extent that it does not show up as a filmthickness buildup or molecular weight change, it can be observed asvariations of microscopic pattern features.

As is known in the art, such highly reactive silanol groups can berendered relatively stable if they are kept in acidic conditions. See C.J. Brinker and G. W. Scherer, “Sol-Gel Science: The Physics andChemistry of Sol-Gel Processing,” Academic Press, San Diego (1990).Further, addition of water improves the shelf stability as disclosed inJ. Appl. Polym. Sci., Vol. 88, 636-640 (2003), JP-A 2004-157469 and JP-A2004-191386. However, the silicon-containing compounds prepared by themethods of these patent publications are not inhibited completely fromcondensation reaction of silanol groups even when any of these means istaken. The silicon-containing compound in the composition slowly alterswith the passage of time, and a silicon-containing film formed from suchan altered composition changes in nature. Then the composition must beheld in a refrigerated or frozen state just until use, and on use, bebrought back to the service temperature (typically 23° C.) and beconsumed quickly.

DISCLOSURE OF THE INVENTION

The present invention relates to a process involving the steps ofdisposing a silicon-containing film on an organic film, disposing aphotoresist film thereon, and forming a resist pattern. An object of thepresent invention is to provide a silicon-containing film-formingcomposition in which (1) the silicon-containing film has alight-absorbing capability to allow for pattern formation even underhigh-NA exposure conditions, (2) the silicon-containing film serves as asatisfactory dry etching mask between the overlying layer or photoresistfilm and the underlying layer or organic film, and (3) the compositionis fully shelf stable. Another object is to provide a substrate havingthe silicon-containing film formed thereon, and a patterning method.

Making investigations on the lithographic properties and stability of asilicon-containing intermediate film-forming composition, the inventorshave found that a composition is obtained by combining (A) asilicon-containing compound obtained through hydrolytic condensation ofa hydrolyzable silicon compound in the presence of an acid catalyst withcomponents (B), (C), (D) and (E) defined below; and that (1) asilicon-containing film formed from the composition holds downreflection under high-NA exposure conditions of either dry or immersionlithography technique when light-absorbing groups are incorporated inthe silicon-containing compound, (2) the silicon-containing film has asufficient etching selectivity ratio to serve as a dry etching mask, and(3) the composition is fully shelf stable so that its lithographyperformance undergoes little or no change over time.

In a first aspect, the invention provides a heat curablesilicon-containing film-forming composition comprising

(A) a silicon-containing compound obtained through hydrolyticcondensation of a hydrolyzable silicon compound in the presence of anacid catalyst,

(B) at least one compound having the general formula (1) or (2):

L_(a)H_(b)X   (1)

wherein L is lithium, sodium, potassium, rubidium or cesium, X is ahydroxyl group or a mono or polyfunctional organic acid residue of 1 to30 carbon atoms, “a” is an integer of at least 1, “b” is 0 or an integerof at least 1, and a+b is equal to the valence of hydroxyl group ororganic acid residue,

M_(a)H_(b)A   (2)

wherein M is sulfonium, iodonium or ammonium, A is X or anon-nucleophilic counter ion, “a” and “b” are as defined above, and a+bis equal to the valence of hydroxyl group, organic acid residue ornon-nucleophilic counter ion,

(C) a mono or polyfunctional organic acid of 1 to 30 carbon atoms,

(D) a mono or polyhydric alcohol substituted with a cyclic ether, and

(E) an organic solvent.

In general, when a hydrolyzable silicon compound (often referred to as“monomer”) is contacted with water in the presence of an acid catalyst,a hydrolyzable substituent group attached to a silicon atom undergoeshydrolysis to form a silanol group. This silanol group further undergoescondensation reaction with another silanol group or unreactedhydrolyzable group, to form a siloxane bond. This reaction occursrepeatedly and consecutively, forming a silicon-containing compoundwhich is referred to as an oligomer or polymer or sometimes sol. At thispoint, among silanol groups produced by hydrolytic reaction in thesystem and available from the monomer, oligomer or polymer, condensationreaction takes place from the highest reactivity groups consecutively tolower reactivity groups, whereupon silanol groups belonging to themonomer, oligomer and polymer are consumed, and a silicon-containingcompound forms instead. This condensation reaction proceeds infinitelyand sometimes until the silicon-containing compound solution haseventually gelled.

However, this condensation reaction is restrained at a specific pH, asreported in C. J. Brinker and G. W. Scherer, “Sol-Gel Science: ThePhysics and Chemistry of Sol-Gel Processing,” Academic Press, San Diego(1990). It is described in J. Appl. Polym. Sci., Vol. 88, 636-640 (2003)that the reaction system is stabilized around pH 1.5, which pH isreferred to as “stable pH,” hereinafter.

It has been found that the composition is improved in shelf stabilitywhen it is controlled at a stable pH with component (C).

Making further investigations on the silicon-containing compound toinhibit condensation between residual silanol groups in thesilicon-containing compound near room temperature, the inventors havefound that a mono or polyhydric alcohol substituted with a cyclic etheris effective as a stabilizer for inhibiting condensation near roomtemperature whereby the composition is outstandingly improved in shelfstability.

Prior art silicon-containing compounds are cured with the aid of a hightemperature of above 300° C. or an acid catalyst derived from a thermalacid generator. According to the invention, when the composition iscoated and heat cured, component (B) acts to alter the pH in proximityto silanol groups from the stable pH region to an unstable pH region(approximately pH 3, see C. J. Brinker and G. W. Scherer, “Sol-GelScience: The Physics and Chemistry of Sol-Gel Processing,” AcademicPress, San Diego (1990)), so that the film can be effectively cured. Ifheat cured under the same conditions as the prior art temperatureconditions, the composition forms a dense film having an increaseddegree of crosslinking as compared with the prior art cured films. Themigration of effective ingredients in the resist film to thesilicon-containing film is prevented, and lithographic propertiesequivalent to ordinary organic ARC are available.

A technical combination of pH control, stabilizer and crosslinkingcatalyst in the above-mentioned way provides a composition which remainsstable at room temperature and is effectively curable at elevatedtemperature. The composition can form a silicon-containingantireflective coating which has stability equivalent to conventionalorganic ARCs.

In a preferred embodiment, the silicon-containing compound (A) comprisesa silicon-containing compound obtained by effecting hydrolyticcondensation of a hydrolyzable silicon compound in the presence of anacid catalyst which is selected from mineral acids, sulfonic acidderivatives and mixtures thereof to form a reaction mixture containingthe silicon-containing compound, and substantially removing the acidcatalyst from the reaction mixture.

The silicon-containing compounds prepared in the prior art are used incoating film-forming compositions without substantially removing theacid catalysts used in hydrolytic is condensation. Due to the carry-overof the condensation reaction catalysts, the compositions fail torestrain condensation of silanol even when they are controlled at astable pH. The resultant compositions are shelf unstable.

If a coating film-forming composition is prepared using from the firstsuch an acidic substance as the hydrolytic condensation catalyst as tokeep the silanol at a stable pH, the condensation reaction of silanolgroups does not proceed to a full extent, leaving more residual silanolgroups. Then, even when the composition is kept at a stable pH, thecomposition yet lacks shelf stability due to superfluous silanol groups.

It has been found that an outstanding improvement in shelf stability isachieved when a silicon-containing compound is obtained by effectinghydrolytic condensation in the presence of an optimum acid catalyst andsubstantially removing the acid catalyst from the reaction mixture, andcomponents (C) and (D) are combined therewith.

In a preferred embodiment, M in formula (2) is tertiary sulfonium,secondary iodonium, or quaternary ammonium. When a compositioncomprising a compound of formula (2) as component (B) is used, a filmhaving an increased degree of crosslinking can be formed followingcuring. This prevents migration of effective ingredients in the resistfilm to the silicon-containing film, and achieves lithographicproperties equivalent to conventional organic ARC.

In a preferred embodiment, M in formula (2) is photo-degradable. Ifcomponent (B) does not completely volatilize off during heat curing,part of component (B) can be left in the silicon-containing film. Thiscomponent can adversely affect the profile of resist pattern. Ifcomponent (B) used is such a compound that the cation moiety is degradedduring exposure, it becomes possible to prevent the profile of resistpattern from being adversely affected during exposure. While the cureability of the silicon-containing compound is drastically improved, asilicon-containing cured film having a good lithographic profile as wellcan be provided.

The preferred silicon-containing film-forming composition may furthercomprise water. When water is added to the composition, silanol groupsin the silicon-containing compound are activated so that a denser filmresults from heat curing reaction. Such a dense film allows theoverlying photoresist layer to exert lithographic performance equivalentto conventional organic ARC.

The silicon-containing film-forming composition may further comprise aphotoacid generator. If component (B) does not completely volatilize offduring heat curing and/or exposure, part of component (B) can be left inthe silicon-containing film, which can adversely affect the profile ofresist pattern. If an acid is generated in the silicon-containing filmduring resist pattern formation, it prevents the profile of resistpattern from being adversely affected.

In a second aspect, the invention provides a silicon-containing film foruse in a multilayer resist process involving the steps of forming anorganic film on a processable substrate, forming a silicon-containingfilm thereon, further forming a resist film thereon from a silicon-freechemically amplified resist composition, patterning the resist film,patterning the silicon-containing film using the resist film pattern,patterning the underlying organic film with the silicon-containing filmpattern serving as an etching mask, and etching the processablesubstrate with the patterned organic film serving as an etching mask,the silicon-containing film being formed from the composition definedabove.

Preferably, the silicon-containing film formed from the composition isused in the multilayer resist process wherein the process furtherinvolves the step of disposing an organic antireflective coating betweenthe resist film and the silicon-containing film.

In a third aspect, the invention provides a substrate having formedthereon, in sequence, an organic film, a silicon-containing film of thecomposition defined above, and a photoresist film.

In a fourth aspect, the invention provides a substrate having formedthereon, in sequence, an organic film, a silicon-containing film of thecomposition defined above, an antireflective coating, and a photoresistfilm.

Preferably, the organic film is a film having an aromatic framework.

In a fifth aspect, the invention provides a method for forming a patternin a substrate, comprising the steps of providing the substrate of thethird aspect, exposing a pattern circuit region of the photoresist filmto radiation, developing the photoresist film with a developer to form aresist pattern, dry etching the silicon-containing film with the resistpattern made an etching mask, etching the organic film with thepatterned silicon-containing film made an etching mask, and etching thesubstrate with the patterned organic film made an etching mask, forforming a pattern in the substrate.

In a sixth aspect, the invention provides a method for forming a patternin a substrate, comprising the steps of providing the substrate of thefourth aspect, exposing a pattern circuit region of the photoresist filmto radiation, developing the photoresist film with a developer to form aresist pattern, dry etching the antireflective coating and thesilicon-containing film with the resist pattern made an etching mask,etching the organic film with the patterned silicon-containing film madean etching mask, and etching the substrate with the patterned organicfilm made an etching mask, for forming a pattern in the substrate.

Preferably, the organic film is a film having an aromatic framework.Typically, the exposing step is carried out by photolithography usingradiation having a wavelength equal to or less than 300 nm.

When the intermediate film and the substrate are used and the substrateis patterned by lithography, a microscopic pattern can be formed in thesubstrate at a high accuracy. When an organic film having an aromaticframework is used, it not only exerts an antireflection effect in thelithography step, but also has sufficient etching resistance in thesubstrate etching step, allowing for etch processing. Particularly whenpatterning is carried out by lithography using radiation with wavelengthequal to or less than 300 nm, especially ArF excimer laser radiation, amicroscopic pattern can be formed at a high accuracy.

BENEFITS OF THE INVENTION

The use of a silicon-containing intermediate film formed from the heatcurable silicon-containing film-forming composition of the inventionallows the overlying photoresist film to be patterned effectively. Sincethe silicon-containing intermediate film provides a high etchingselectivity relative to an organic material, the formed photoresistpattern can be transferred in sequence to the silicon-containingintermediate film and the organic undercoat film by a dry etchingprocess. Finally, the substrate can be processed at a high accuracywhile the organic undercoat film serves as an etching mask. Thecomposition of the invention is effective in minimizing the occurrenceof pattern defects after lithography and is shelf stable.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the specification, the singular forms “a,” “an” and “the” includeplural referents unless the context clearly dictates otherwise.

The notation (Cn-Cm) means a group containing from n to m carbon atomsper group.

The terms “mono or polyfunctional” and “mono or polyhydric” are used ina similar meaning. For example, the “mono or polyfunctional” compound isa compound having a functionality of 1, 2 or more.

Component (A) in the heat curable silicon-containing film-formingcomposition of the invention is a silicon-containing compound which isobtained by effecting hydrolytic condensation of a hydrolyzable siliconcompound or monomer in the presence of an acid catalyst. The preferredmethod of preparing the silicon-containing compound is exemplifiedbelow, but not limited thereto.

The starting material or monomer may have the following general formula(3):

R¹ _(m1)R² _(m2)R³ _(m3)Si(OR)_((4-m1-m2-m3))   (3)

wherein R is an alkyl group of 1 to 3 carbon atoms, each of R¹, R² andR³, which may be the same or different, is hydrogen or a monovalentorganic group of 1 to 30 carbon atoms, m1, m2 and m3 are equal to 0 or1, the sum of m1+m2+m3 is equal to 0 to 3, and preferably 0 or 1. One ora mixture of two or more selected from the monomers having formula (3)is subjected to hydrolytic condensation.

As used herein, the term “organic group” refers to a group containingcarbon, specifically carbon and hydrogen, and optionally nitrogen,oxygen, sulfur, silicon and other elements. The organic groupsrepresented by R¹, R² and R³ include unsubstituted monovalenthydrocarbon groups, such as straight, branched or cyclic alkyl, alkenyl,alkynyl, aryl and aralkyl groups, substituted forms of the foregoinghydrocarbon groups in which one or more hydrogen atoms are substitutedby epoxy, alkoxy, hydroxyl or the like, groups of the general formula(4), shown later, for example, groups which are separated by such agroup as —O—, —CO—, —OCO—, —COO—, or —OCOO—, and organic groupscontaining a silicon-silicon bond.

Preferred examples of R¹, R² and R³ in the monomers of formula (3)include hydrogen, alkyl groups such as methyl, ethyl, n-propyl,iso-propyl, n-butyl, iso-butyl, sec-butyl, t-butyl, n-pentyl,2-ethylbutyl, 3-ethylbutyl, 2,2-diethylpropyl, cyclopentyl, n-hexyl, andcyclohexyl, alkenyl groups such as vinyl and allyl, alkynyl groups suchas ethynyl, and light-absorbing groups like aryl groups such as phenyland tolyl, and aralkyl groups such as benzyl and phenethyl.

Examples of suitable tetraalkoxysilanes corresponding to formula (3)wherein m1=0, m2=0 and m3=0 include tetramethoxysilane,tetraethoxysilane, tetra-n-propoxysilane, and tetra-iso-propoxysilane.Of these, preferred are tetramethoxysilane and tetraethoxysilane.

Examples of suitable trialkoxysilanes corresponding to formula (3)wherein m1=0, m2=0 and m3=0 include trimethoxysilane, triethoxysilane,tri-n-propoxysilane, triisopropoxysilane, methyltrimethoxysilane,methyltriethoxysilane, methyltri-n-propoxysilane,methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane,ethyltri-n-propoxysilane, ethyltriisopropoxysilane,vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri-n-propoxysilane,vinyltriisopropoxysilane, n-propyltrimethoxysilane,n-propyltriethoxysilane, n-propyltri-n-propoxysilane,n-propyltriisopropoxysilane, isopropyltrimethoxysilane,isopropyltriethoxysilane, isopropyltri-n-propoxysilane,isopropyltriisopropoxysilane, n-butyltrimethoxysilane,n-butyltriethoxysilane, n-butyltri-n-propoxysilane,n-butyltriisopropoxysilane, sec-butyltrimethoxysilane,sec-butyltriethoxysilane, sec-butyltri-n-propoxysilane,sec-butyltriisopropoxysilane, t-butyltrimethoxysilane,t-butyltriethoxysilane, t-butyltri-n-propoxysilane,t-butyltriisopropoxysilane, cyclopropyltrimethoxysilane,cyclopropyltriethoxysilane, cyclopropyltri-n-propoxysilane,cyclopropyltriisopropoxysilane, cyclobutyltrimethoxysilane,cyclobutyltriethoxysilane, cyclobutyltri-n-propoxysilane,cyclobutyltriisopropoxysilane, cyclopentyltrimethoxysilane,cyclopentyltriethoxysilane, cyclopentyltri-n-propoxysilane,cyclopentyltriisopropoxysilane, cyclohexyltrimethoxysilane,cyclohexyltriethoxysilane, cyclohexyltri-n-propoxysilane,cyclohexyltrlisopropoxysilane, cyclohexenyltrimethoxysilane,cyclohexenyltriethoxysilane, cyclohexenyltri-n-propoxysilane,cyclohexenyltriisopropoxysilane, cyclohexenylethyltrimethoxysilane,cyclohexenylethyltriethoxysilane, cyclohexenylethyltri-n-propoxysilane,cyclohexenylethyltriisopropoxysilane, cyclooctanyltrimethoxysilane,cyclooctanyltriethoxysilane, cyclooctanyltri-n-propoxysilane,cyclooctanyltriisopropoxysilane, cyclopentadienylpropyltrimethoxysilane,cyclopentadienylpropyltriethoxysilane,cyclopentadienylpropyltri-n-propoxysilane,cyclopentadienylpropyltriisopropoxysilane,bicycloheptenyltrimethoxysilane, bicycloheptenyltriethoxysilane,bicycloheptenyltri-n-propoxysilane, bicycloheptenyltriisopropoxysilane,bicycloheptyltrimethoxysilane, bicycloheptyltriethoxysilane,bicycloheptyltri-n-propoxysilane, bicycloheptyltriisopropoxysilane,adamantyltrimethoxysilane, adamantyltriethoxysilane,adamantyltri-n-propoxysilane, adamantyltriisopropoxysilane, etc.Suitable light-absorbing monomers include phenyltrimethoxysilane,phenyltriethoxysilane, phenyltri-n-propoxysilane,phenyltriisopropoxysilane, benzyltrimethoxysilane,benzyltriethoxysilane, benzyltri-n-propoxysilane,benzyltriisopropoxysilane, tolyltrimethoxysilane, tolyltriethoxysilane,tolyltri-n-propoxysilane, tolyltriisopropoxysilane,phenethyltrimethoxysilane, phenethyltriethoxysilane,phenethyltri-n-propoxysilane, phenethyltriisopropoxysilane,naphthyltrimethoxysilane, naphthyltriethoxysilane,naphthyltri-n-propoxysilane, naphthyltriisopropoxysilane, etc.

Of these, preferred are methyltrimethoxysilane, methyltriethoxysilane,ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane,vinyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane,isopropyltrimethoxysilane, isopropyltriethoxysilane,n-butyltrimethoxysilane, n-butyltriethoxysilane,isobutyltrimethoxysilane, isobutyltriethoxysilane,allyltrimethoxysilane, allyltriethoxysilane,cyclopentyltrimethoxysilane, cyclopentyltriethoxysilane,cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane,cyclohexenyltrimethoxysilane, cyclohexenyltriethoxysilane,phenyltrimethoxysilane, phenyltriethoxysilane, benzyltrimethoxysilane,benzyltriethoxysilane, phenethyltrimethoxysilane, andphenethyltriethoxysilane.

Examples of suitable dialkoxysilanes corresponding to formula (3)wherein m1=1, m2=1 and m3=0 include dimethyldimethoxysilane,dimethyldiethoxysilane, methylethyldimethoxysilane,methylethyldiethoxysilane, dimethyldi-n-propoxysilane,dimethyldiisopropoxysilane, diethyldimethoxysilane,diethyldiethoxysilane, diethyldi-n-propoxysilane,diethyldiisopropoxysilane, di-n-propyldimethoxysilane,di-n-propyldiethoxysilane, di-n-propyl-di-n-propoxysilane,di-n-propyldiisopropoxysilane, diisopropyldimethoxysilane,diisopropyldiethoxysilane, diisopropyldi-n-propoxysilane,diisopropyldiisopropoxysilane, di-n-butyldimethoxysilane,di-n-butyldiethoxysilane, di-n-butyldi-n-propoxysilane,di-n-butyldiisopropoxysilane, di-sec-butyldimethoxysilane,di-sec-butyldiethoxysilane, di-sec-butyldi-n-propoxysilane,di-sec-butyldiisopropoxysilane, di-t-butyldimethoxysilane,di-t-butyldiethoxysilane, di-t-butyldi-n-propoxysilane,di-t-butyldiisopropoxysilane, dicyclopropyldimethoxysilane,dicyclopropyldiethoxysilane, dicyclopropyldi-n-propoxysilane,dicyclopropyldiisopropoxysilane, dicyclobutyldimethoxysilane,dicyclobutyldiethoxysilane, dicyclobutyldi-n-propoxysilane,dicyclobutyldiisopropoxysilane, dicyclopentyldimethoxysilane,dicyclopentyldiethoxysilane, dicyclopentyldi-n-propoxysilane,dicyclopentyldiisopropoxysilane, dicyclohexyldimethoxysilane,dicyclohexyldiethoxysilane, dicyclohexyldi-n-propoxysilane,dicyclohexyldiisopropoxysilane, dicyclohexenyldimethoxysilane,dicyclohexenyldiethoxysilane, dicyclohexenyldi-n-propoxysilane,dicyclohexenyldiisopropoxysilane, dicyclohexenylethyldimethoxysilane,dicyclohexenylethyldiethoxysilane,dicyclohexenylethyldi-n-propoxysilane,dicyclohexenylethyldiisopropoxysilane, dicyclooctanyldimethoxysilane,dicyclooctanyldiethoxysilane, dicyclooctanyldi-n-propoxysilane,dicyclooctanyldiisopropoxysilane,dicyclopentadienylpropyldimethoxysilane,dicyclopentadienylpropyldiethoxysilane,dicyclopentadienylpropyldi-n-propoxysilane,dicyclopentadienylpropyldiisopropoxysilane,bisbicycloheptenyldimethoxysilane, bisbicycloheptenyldiethoxysilane,bisbicycloheptenyldi-n-propoxysilane,bisbicycloheptenyldiisopropoxysilane, bisbicycloheptyldimethoxysilane,bisbicycloheptyldiethoxysilane, bisbicycloheptyldi-n-propoxysilane,bisbicycloheptyldiisopropoxysilane, bisadamantyldimethoxysilane,bisadamantyldiethoxysilane, bisadamantyldi-n-propoxysilane,bisadamantyldiisopropoxysilane, etc. Suitable light-absorbing monomersinclude diphenyldimethoxysilane, diphenyldiethoxysilane,methylphenyldimethoxysilane, methylphenyldiethoxysilane,diphenyldi-n-propoxysilane, and diphenyldiisopropoxysilane.

Of these, preferred are dimethyldimethoxysilane, dimethyldiethoxysilane,diethyldimethoxysilane, diethyldiethoxysilane,methylethyldimethoxysilane, methylethyldiethoxysilane,di-n-propyldimethoxysilane, di-n-butyldimethoxysilane,methylphenyldimethoxysilane, and methylphenyldiethoxysilane.

Examples of suitable monoalkoxysilanes corresponding to formula (3)wherein m1=1, m2=1 and m3=1 include trimethylmethoxysilane,trimethylethoxysilane, dimethylethylmethoxysilane, anddimethylethylethoxysilane. Suitable light-absorbing monomers includedimethylphenylmethoxysilane, dimethylphenylethoxysilane,dimethylbenzylmethoxysilane, dimethylbenzylethoxysilane,dimethylphenethylmethoxysilane, and dimethylphenethylethoxysilane.

Of these, preferred are trimethylmethoxysilane,dimethylethylmethoxysilane, dimethylphenylmethoxysilane,dimethylbenzylmethoxysilane, and dimethylphenethylmethoxysilane.

Other exemplary organic groups represented by R¹, R² and R³ includeorganic groups having at least one carbon-oxygen single bond orcarbon-oxygen double bond. Illustrative of such groups are organicgroups having at least one group selected from among epoxy, ester,alkoxy, and hydroxyl groups. Examples of organic groups having at leastone carbon-oxygen single bond or carbon-oxygen double bond in formula(3) include those of the following general formula (4).

(P-Q₁-(S₁)_(v1)-Q₂-)_(u)-(T)_(v2)-Q₃-(S₂)_(v3)-Q₄-   (4)

Herein, P is a hydrogen atom, hydroxyl group, epoxy ring of the formula:

C₁-C₄ alkoxy group, C₁-C₆ alkylcarbonyloxy group, or C₁-C₆ alkylcarbonylgroup, Q₁, Q₂, Q₃ and Q₄ are each independently —CqH_((2q-p))P_(p)—wherein P is as defined above, p is an integer of 0 to 3, and q is aninteger of 0 to 10 (with the proviso that q=0 denotes a single bond); uis an integer of 0 to 3, S₁ and S₂ are each independently —O—, —CO—,—OCO—, —COO—, or —OCOO—; v1, v2 and v3 are each independently 0 or 1. Tis a divalent group of aliphatic or aromatic ring which may contain aheteroatom, typically oxygen, examples of which are shown below.Notably, the sites on T where T is bonded to Q₂ and Q₃ are notparticularly limited and may be selected appropriate in accordance withreactivity dependent on steric factors and the availability ofcommercial reagents used in the reaction.

Preferred examples of organic groups having at least one carbon-oxygensingle bond or carbon-oxygen double bond in formula (3) are given below.It is noted that in the following formulae, (Si) is depicted to indicatethe bonding site to silicon.

Also included in the organic groups of R¹, R² and R³ are organic groupshaving a silicon-silicon bond, examples of which are given below.

One or more monomers are selected from the foregoing monomers and usedas the starting material for reaction to form the silicon-containingcompound. Where two or more monomers are used, they may be mixed beforeor during reaction.

The silicon-containing compound may be prepared by subjecting a suitablemonomer(s) to hydrolytic condensation in the presence of an acidcatalyst which is selected from mineral acids, aliphatic and aromaticsulfonic acids and mixtures thereof. Suitable acid catalysts which canbe used include hydrofluoric acid, hydrochloric acid, hydrobromic acid,sulfuric acid, nitric acid, perchloric acid, phosphoric acid,methanesulfonic acid, benzenesulfonic acid, and toluenesulfonic acid.The catalyst may be used in an amount of 10⁻⁶ to 10 moles, preferably10⁻⁵ to 5 moles, and more preferably 10⁻⁴ to 1 mole per mole of thesilicon monomer(s).

The amount of water used in hydrolytic condensation of the monomer(s) toform the silicon-containing compound is preferably 0.01 to 100 moles,more preferably 0.05 to 50 moles, even more preferably 0.1 to 30 molesper mole of hydrolyzable substituent group(s) on the monomer(s). Theaddition of more than 100 moles of water is uneconomical in that theapparatus used for reaction becomes accordingly larger.

In one exemplary operating procedure, the monomer is added to an aqueoussolution of the catalyst to start hydrolytic condensation. At thispoint, an organic solvent may be added to the aqueous catalyst solutionand/or the monomer may be diluted with an organic solvent. The reactiontemperature is 0 to 100° C., preferably 5 to 80° C. In the preferredprocedure, the monomer is added dropwise at a temperature of 5 to 80°C., after which the reaction mixture is matured at 20 to 80° C.

Examples of the organic solvent which can be added to the aqueouscatalyst solution or to the monomer for dilution include methanol,ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol,2-methyl-1-propanol, acetone, acetonitrile, tetrahydrofuran, toluene,hexane, ethyl acetate, cyclohexanone, methyl-2-n-amylketone, butane diolmonomethyl ether, propylene glycol monomethyl ether, ethylene glycolmonomethyl ether, butane diol monoethyl ether, propylene glycolmonoethyl ether, ethylene glycol monoethyl ether, propylene glycoldimethyl ether, diethylene glycol dimethyl ether, propylene glycolmonomethyl ether acetate (PGMEA), propylene glycol monoethyl etheracetate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate,ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate,propylene glycol mono-tert-butyl ether acetate, γ-butyrolactone, andmixtures thereof.

Among others, water-soluble solvents are preferred. Suitablewater-soluble solvents include alcohols such as methanol, ethanol,1-propanol and 2-propanol, polyhydric alcohols such as ethylene glycoland propylene glycol, polyhydric alcohol condensation derivatives suchas butane diol monomethyl ether, propylene glycol monomethyl ether,ethylene glycol monomethyl ether, butane diol monoethyl ether, propyleneglycol monoethyl ether, ethylene glycol monoethyl ether, butane diolmonopropyl ether, propylene glycol monopropyl ether, and ethylene glycolmonopropyl ether, acetone, acetonitrile, and tetrahydrofuran. Of these,those solvents having a boiling point equal to or lower than 100° C. arepreferred.

The amount of the organic solvent used is 0 to 1,000 ml, preferably 0 to500 ml per mole of the monomer. Too much amounts of the organic solventare uneconomical in that the reactor must be of larger volume.

Thereafter, neutralization reaction of the catalyst is carried out ifnecessary, and the alcohol produced by the hydrolytic condensationreaction is removed under reduced pressure, yielding an aqueous reactionmixture. The amount of an alkaline compound used for neutralizataion ispreferably 0.1 to 2 equivalents relative to the acid used as thecatalyst. Any alkaline compound may be used as long as it exhibitsalkalinity in water.

Subsequently, the alcohol produced by the hydrolytic condensationreaction must be removed from the reaction mixture. To this end, thereaction mixture is heated at a temperature which is preferably 0 to100° C., more preferably 10 to 90° C., even more preferably 15 to 80°C., although the temperature depends on the type of organic solventadded and the type of alcohol produced. The reduced pressure ispreferably atmospheric or subatmospheric, more preferably equal to orless than 80 kPa in absolute pressure, and even more preferably equal toor less than 50 kPa in absolute pressure, although the pressure varieswith the type of organic solvent and alcohol to be removed and thevacuum pump, condenser, and heating temperature. Although an accuratedetermination of the amount of alcohol removed at this point isdifficult, it is desired to remove about 80% by weight or more of thealcohol produced.

Next, the acid catalyst used in the hydrolytic condensation may beremoved from the reaction mixture. This is achieved by extracting thesilicon-containing compound with an organic solvent. The organic solventused herein is preferably a solvent in which the silicon-containingcompound is dissolvable and which provides two-layer separation whenmixed with water. Suitable organic solvents include methanol, ethanol,1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol,acetone, tetrahydrofuran, toluene, hexane, ethyl acetate, cyclohexanone,methyl-2-n-amylketone, butane diol monomethyl ether, propylene glycolmonomethyl ether, ethylene glycol monomethyl ether, butane diolmonoethyl ether, propylene glycol monoethyl ether, ethylene glycolmonoethyl ether, butane diol monopropyl ether, propylene glycolmonopropyl ether, ethylene glycol monopropyl ether, propylene glycoldimethyl ether, diethylene glycol dimethyl ether, propylene glycolmonomethyl ether acetate, propylene glycol monoethyl ether acetate,ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, propyleneglycol mono-tert-butyl ether acetate, γ-butyrolactone, methyl isobutylketone, cyclopentyl methyl ether, and mixtures thereof.

It is also acceptable to use a mixture of a water-soluble organicsolvent and a substantially water-insoluble organic solvent. Exemplarymixtures include, but are not limited to, combinations of methanol+ethylacetate, ethanol+ethyl acetate, 1-propanol+ethyl acetate,2-propanol+ethyl acetate, butane diol monomethyl ether+ethyl acetate,propylene glycol monomethyl ether+ethyl acetate, ethylene glycolmonomethyl ether+ethyl acetate, butane diol monoethyl ether+ethylacetate, propylene glycol monoethyl ether+ethyl acetate, ethylene glycolmonoethyl ether+ethyl acetate, butane diol monopropyl ether+ethylacetate, propylene glycol monopropyl ether+ethyl acetate, ethyleneglycol monopropyl ether+ethyl acetate, methanol+methyl isobutyl ketone(MIK), ethanol+MIK, 1-propanol+MIK, 2-propanol+MIK, propylene glycolmonomethyl ether+MIK, ethylene glycol monomethyl ether+MIK, propyleneglycol monoethyl ether+MIK, ethylene glycol monoethyl ether+MIK,propylene glycol monopropyl ether+MIK, ethylene glycol monopropylether+MIK, methanol+cyclopentyl methyl ether, ethanol+cyclopentyl methylether, 1-propanol+cyclopentyl methyl ether, 2-propanol+cyclopentylmethyl ether, propylene glycol monomethyl ether+cyclopentyl methylether, ethylene glycol monomethyl ether+cyclopentyl methyl ether,propylene glycol monoethyl ether+cyclopentyl methyl ether, ethyleneglycol monoethyl ether+cyclopentyl methyl ether, propylene glycolmonopropyl ether+cyclopentyl methyl ether, ethylene glycol monopropylether+cyclopentyl methyl ether, methanol+propylene glycol methyl etheracetate (PGMEA), ethanol+PGMEA, 1-propanol+PGMEA, 2-propanol+PGMEA,propylene glycol monomethyl ether+PGMEA, ethylene glycol monomethylether+PGMEA, propylene glycol monoethyl ether+PGMEA, ethylene glycolmonoethyl ether+PGMEA, propylene glycol monopropyl ether+PGMEA, andethylene glycol monopropyl ether+PGMEA.

A mixing proportion of the water-soluble organic solvent and thesubstantially water-insoluble organic solvent may be determined asappropriate although it is a usual practice to use 0.1 to 1,000 parts,preferably 1 to 500 parts, and more preferably 2 to 100 parts by weightof the water-soluble organic solvent per 100 parts by weight of thesubstantially water-insoluble organic solvent.

Subsequent step is to wash with neutral water. The water used forwashing may be deionized water or ultrapure water. The amount of wateris 0.01 to 100 liters (L), preferably 0.05 to 50 L, more preferably 0.1to 5 L per liter of the silicon-containing compound solution. Thewashing step may be carried out by feeding both the liquids into acommon vessel, agitating the contents, allowing the mixture to stand andto separate into two layers, and removing the water layer. The number ofwashing steps may be one or more, although the repetition of more than10 washing steps does not achieve the effect corresponding to such anumber of steps. Preferably the number of washing steps is from 1 toabout 5.

Other methods of removing the acid catalyst include the use of anion-exchange resin, and neutralization with epoxy compounds such asethylene oxide and propylene oxide followed by removal. A proper methodmay be selected from among these methods in accordance with the acidcatalyst used in the reaction.

As used herein, the term “substantially removing the acid catalyst”means that it is acceptable that no more than 10% by weight, preferablyno more than 5% by weight of the acid catalyst used in the reaction isleft in the silicon-containing compound.

Since the water washing operation may sometimes achieve an effectsubstantially equivalent to a fractionation operation in that part ofthe silicon-containing compound is carried away to the water layer, thenumber of washing cycles and the amount of water may be determinedappropriate depending on the relative extent of catalyst removal andfractionation effects.

A final solvent is added to the silicon-containing compound solutionfrom which the acid catalyst may or may not have been removed, forinducing solvent exchange under a reduced pressure, yielding asilicon-containing compound solution. The temperature for solventexchange is preferably 0 to 100° C., more preferably 10 to 90° C., evenmore preferably 15 to 80° C., although the temperature depends on thetype of reaction or extraction solvent to be removed. The reducedpressure is preferably atmospheric or subatmospheric, more preferablyequal to or less than 80 kPa in absolute pressure, and even morepreferably equal to or less than 50 kPa in absolute pressure, althoughthe pressure varies with the type of extraction solvent to be removedand the vacuum pump, condenser, and heating temperature.

As a result of solvent exchange, the silicon-containing compoundsometimes becomes unstable. Such instability occurs depending on thecompatibility of the silicon-containing compound with the final solvent.Component (C) to be described later may be added as a stabilizer inorder to prevent such inconvenience. The amount of component (C) addedis 0 to 25 parts, preferably 0 to 15 parts, more preferably 0 to 5 partsby weight per 100 parts by weight of the silicon-containing compound inthe solution prior to the solvent exchange. When added, the preferredamount of component (C) is at least 0.5 part by weight. If necessary forthe solution before the solvent exchange, component (C) may be addedbefore the solvent exchange operation is carried out.

If the silicon-containing compound is concentrated above a certainlevel, it undergoes condensation reaction so that it converts to thestate which can no longer be re-dissolved in organic solvents. It isthen recommended that the silicon-containing compound be kept insolution form at an adequate concentration. The concentration isspecifically equal to or less than 50% by weight, more specificallyequal to or less than 40% by weight, and even more specifically equal toor less than 30% by weight.

The final solvent added to the silicon-containing compound solution ispreferably an alcoholic solvent, examples of which include monoalkylethers of ethylene glycol, diethylene glycol, triethylene glycol and thelike, and monoalkyl ethers of propylene glycol, dipropylene glycol andthe like. Preferred examples include butane diol monomethyl ether,propylene glycol monomethyl ether, ethylene glycol monomethyl ether,butane diol monoethyl ether, propylene glycol monoethyl ether, ethyleneglycol monoethyl ether, butane diol monopropyl ether, propylene glycolmonopropyl ether, and ethylene glycol monopropyl ether.

In another exemplary reaction procedure, water or a water-containingorganic solvent is added to the monomer or an organic solvent solutionof the monomer to start hydrolytic reaction. At this point, the catalystmay be added to the monomer or an organic solvent solution of themonomer, or water or a water-containing organic solvent. The reactiontemperature is 0 to 100° C., preferably 10 to 80° C. In the preferredprocedure, water is added dropwise at a temperature of 10 to 50° C.,after which the reaction mixture is matured at 20 to 80 C.

Of the organic solvents, if used, water-soluble solvents are preferred.Suitable organic solvents include methanol, ethanol, 1-propanol,2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, acetone,tetrahydrofuran, acetonitrile, and polyhydric alcohol condensationderivatives such as butane diol monomethyl ether, propylene glycolmonomethyl ether, ethylene glycol monomethyl ether, butane diolmonoethyl ether, propylene glycol monoethyl ether, ethylene glycolmonoethyl ether, butane diol monopropyl ether, propylene glycolmonopropyl ether, ethylene glycol monopropyl ether, propylene glycoldimethyl ether, diethylene glycol dimethyl ether, propylene glycolmonomethyl ether acetate, propylene glycol monoethyl ether acetate, andpropylene glycol monopropyl ether, and mixtures thereof.

The amount of the organic solvent used may be the same as describedabove for the one procedure. The resulting reaction mixture ispost-treated as described above for the one procedure, yielding asilicon-containing compound.

The molecular weight of the resulting silicon-containing compound may beadjusted by a choice of monomer(s) and by control of reaction conditionsduring polymerization. Compounds having a weight average molecularweight in excess of 100,000 may produce foreign matter or coating specksin some cases. Then the silicon-containing compound preferably has aweight average molecular weight equal to or less than 100,000, morepreferably 200 to 50,000, and even more preferably 300 to 30,000. It isnoted that the weight average molecular weight is determined by gelpermeation chromatography (GPC) using an RI detector and polystyrenestandards.

In the silicon-containing film-forming composition of the invention, twoor more silicon-containing compounds which differ in composition and/orreaction conditions may be contained as long as they are prepared underacidic conditions.

According to the invention, a silicon-containing film-formingcomposition can be formulated by compounding (A) the silicon-containingcompound described above with (B) a thermal crosslink accelerator, (C)an acid, (D) a stabilizer, and (E) an organic solvent.

The composition of the invention must contain a thermal crosslinkaccelerator as component (B) to further accelerate crosslinking reactionin forming a silicon-containing film. Included in the accelerator arecompounds having the general formulae (1) and (2).

L_(a)H_(b)X   (1)

Herein L is lithium, sodium, potassium, rubidium or cesium, X is ahydroxyl group or a mono or polyfunctional organic acid residue of 1 to30 carbon atoms, “a” is an integer of at least 1, “b” is 0 or an integerof at least 1, and a+b is equal to the valence of hydroxyl group ororganic acid residue.

M_(a)H_(b)A   (2)

Herein M is sulfonium, iodonium or ammonium, preferably tertiarysulfonium, secondary iodonium, or quaternary ammonium, and morepreferably a photo-degradable onium like triphenylsulfonium ordiphenyliodonium. A is as defined above for X or a non-nucleophiliccounter ion, “a” and “b” are as defined above, and a+b is equal to thevalence of hydroxyl group, organic acid residue or non-nucleophiliccounter ion.

Exemplary of the compound of formula (1) are alkali metal salts oforganic acids, for example, salts of lithium, sodium, potassium,rubidium and cesium with hydroxide, formic acid, acetic acid, propionicacid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid,octanoic acid, nonanoic acid, decanoic acid, oleic acid, stearic acid,linoleic acid, linolenic acid, benzoic acid, phthalic acid, isophthalicacid, terephthalic acid, salicylic acid, trifluoroacetic acid,monochloroacetic acid, dichloroacetic acid, trichloroacetic acid andother monofunctional acids; and salts of lithium, sodium, potassium,rubidium and cesium with mono- or di-functional acids such as oxalicacid, malonic acid, methylmalonic acid, ethylmalonic acid, propylmalonicacid, butylmalonic acid, dimethylmalonic acid, diethylmalonic acid,succinic acid, methylsuccinic acid, glutaric acid, adipic acid, itaconicacid, maleic acid, fumaric acid, citraconic acid, citric acid, andcarbonic acid.

Illustrative examples include

lithium formate, lithium acetate, lithium propionate, lithium butanoate,lithium pentanoate, lithium hexanoate, lithium heptanoate, lithiumoctanoate, lithium nonanoate, lithium decanoate, lithium oleate, lithiumstearate, lithium linoleate, lithium linolenate, lithium benzoate,lithium phthalate, lithium isophthalate, lithium terephthalate, lithiumsalicylate, lithium trifluoromethanesulfonate, lithium trifluoroacetate,lithium monochloroacetate, lithium dichloroacetate, lithiumtrichloroacetate, lithium hydroxide, lithium hydrogen oxalate, lithiumhydrogen malonate, lithium hydrogen methylmalonate, lithium hydrogenethylmalonate, lithium hydrogen propylmalonate, lithium hydrogenbutylmalonate, lithium hydrogen dimethylmalonate, lithium hydrogendiethylmalonate, lithium hydrogen succinate, lithium hydrogenmethylsuccinate, lithium hydrogen glutarate, lithium hydrogen adipate,lithium hydrogen itaconate, lithium hydrogen maleate, lithium hydrogenfumarate, lithium hydrogen citraconate, lithium hydrogen citrate,lithium hydrogen carbonate, lithium oxalate, lithium malonate, lithiummethylmalonate, lithium ethylmalonate, lithium propylmalonate, lithiumbutylmalonate, lithium dimethylmalonate, lithium diethylmalonate,lithium succinate, lithium methylsuccinate, lithium glutarate, lithiumadipate, lithium itaconate, lithium maleate, lithium fumarate, lithiumcitraconate, lithium citrate, lithium carbonate;

sodium formate, sodium acetate, sodium propionate, sodium butanoate,sodium pentanoate, sodium hexanoate, sodium heptanoate, sodiumoctanoate, sodium nonanoate, sodium decanoate, sodium oleate, sodiumstearate, sodium linoleate, sodium linolenate, sodium benzoate, sodiumphthalate, sodium isophthalate, sodium terephthalate, sodium salicylate,sodium trifluoromethanesulfonate, sodium trifluoroacetate, sodiummonochloroacetate, sodium dichloroacetate, sodium trichloroacetate,sodium hydroxide, sodium hydrogen oxalate, sodium hydrogen malonate,sodium hydrogen methylmalonate, sodium hydrogen ethylmalonate, sodiumhydrogen propylmalonate, sodium hydrogen butylmalonate, sodium hydrogendimethylmalonate, sodium hydrogen diethylmalonate, sodium hydrogensuccinate, sodium hydrogen methylsuccinate, sodium hydrogen glutarate,sodium hydrogen adipate, sodium hydrogen itaconate, sodium hydrogenmaleate, sodium hydrogen fumarate, sodium hydrogen citraconate, sodiumhydrogen citrate, sodium hydrogen carbonate, sodium oxalate, sodiummalonate, sodium methylmalonate, sodium ethylmalonate, sodiumpropylmalonate, sodium butylmalonate, sodium dimethylmalonate, sodiumdiethylmalonate, sodium succinate, sodium methylsuccinate, sodiumglutarate, sodium adipate, sodium itaconate, sodium maleate, sodiumfumarate, sodium citraconate, sodium citrate, sodium carbonate;

potassium formate, potassium acetate, potassium propionate, potassiumbutanoate, potassium pentanoate, potassium hexanoate, potassiumheptanoate, potassium octanoate, potassium nonanoate, potassiumdecanoate, potassium oleate, potassium stearate, potassium linoleate,potassium linolenate, potassium benzoate, potassium phthalate, potassiumisophthalate, potassium terephthalate, potassium salicylate, potassiumtrifluoromethanesulfonate, potassium trifluoroacetate, potassiummonochloroacetate, potassium dichloroacetate, potassiumtrichloroacetate, potassium hydroxide, potassium hydrogen oxalate,potassium hydrogen malonate, potassium hydrogen methylmalonate,potassium hydrogen ethylmalonate, potassium hydrogen propylmalonate,potassium hydrogen butylmalonate, potassium hydrogen dimethylmalonate,potassium hydrogen diethylmalonate, potassium hydrogen succinate,potassium hydrogen methylsuccinate, potassium hydrogen glutarate,potassium hydrogen adipate, potassium hydrogen itaconate, potassiumhydrogen maleate, potassium hydrogen fumarate, potassium hydrogencitraconate, potassium hydrogen citrate, potassium hydrogen carbonate,potassium oxalate, potassium malonate, potassium methylmalonate,potassium ethylmalonate, potassium propylmalonate, potassiumbutylmalonate, potassium dimethylmalonate, potassium diethylmalonate,potassium succinate, potassium methylsuccinate, potassium glutarate,potassium adipate, potassium itaconate, potassium maleate, potassiumfumarate, potassium citraconate, potassium citrate, potassium carbonate,etc.

The compounds of formula (2) include sulfonium, iodonium and ammoniumcompounds having the formulae (Q-1), (Q-2), and (Q-3), respectively.

Herein, R²⁰⁴, R²⁰⁵ and R²⁰⁶ are each independently a straight, branchedor cyclic alkyl, alkenyl, oxoalkyl or oxoalkenyl group of 1 to 12 carbonatoms, substituted or unsubstituted aryl group of 6 to 20 carbon atoms,aralkyl or aryloxoalkyl group of 7 to 12 carbon atoms, in which some orall hydrogen atoms may be substituted by alkoxy groups or the like. Apair of R²⁰⁵ and R²⁰⁶ may form a ring, and each is a C₁-C₆ alkylenegroup when they form a ring. A⁻ is a non-nucleophilic counter ion. R²⁰⁷,R²⁰⁸, R²⁰⁹, and R²¹⁰ are as defined for R²⁰⁴, R²⁰⁵ and R²⁰⁶, and mayalso be hydrogen. A pair of R²⁰⁷ and R²⁰⁸ or a combination of R²⁰⁷, R²⁰⁸and R²⁰⁹ may form a ring, and each is a C₃-C₁₀ alkylene group when theyform a ring.

R²⁰⁴, R²⁰⁵, R²⁰⁶, R²⁰⁷, R²⁰⁸, R²⁰⁹, and R²¹⁰ may be the same ordifferent. Suitable alkyl groups include methyl, ethyl, propyl,isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl,cyclopentyl, cyclohexyl, cycloheptyl, cyclopropylmethyl,4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl. Suitablealkenyl groups include vinyl, allyl, propenyl, butenyl, hexenyl, andcyclohexenyl. Suitable oxoalkyl groups include 2-oxocyclopentyl and2-oxocyclohexyl as well as 2-oxopropyl, 2-cyclopentyl-2-oxoethyl,2-cyclohexyl-2-oxoethyl, and 2-(4-methylcyclohexyl)-2-oxoethyl. Suitablearyl groups include phenyl and naphthyl, alkoxyphenyl groups such asp-methoxyphenyl, m-methoxyphenyl, o-methoxyphenyl, ethoxyphenyl,p-tert-butoxyphenyl, and m-tert-butoxyphenyl, alkylphenyl groups such as2-methylphenyl, 3-methylphenyl, 4-methylphenyl, ethylphenyl,4-tert-butylphenyl, 4-butylphenyl, and dimethylphenyl, alkylnaphthylgroups such as methylnaphthyl and ethylnaphthyl, alkoxynaphthyl groupssuch as methoxynaphthyl and ethoxynaphthyl, dialkylnaphthyl groups suchas dimethylnaphthyl and diethylnaphthyl, and dialkoxynaphthyl groupssuch as dimethoxynaphthyl and diethoxynaphthyl. Suitable aralkyl groupsinclude benzyl, phenylethyl and phenethyl. Suitable aryloxoalkyl groupsinclude 2-aryl-2-oxoethyl groups such as 2-phenyl-2-oxoethyl,2-(1-naphthyl)-2-oxoethyl and 2-(2-naphthyl)-2-oxoethyl.

Examples of the non-nucleophilic counter ion represented by A⁻ includehydroxyl, formate, acetate, propionate, butanoate, pentanoate,hexanoate, heptanoate, octanoate, nonanoate, decanoate, oleate,stearate, linoleate, linolenate, benzoate, p-methylbenzoate,p-t-butylbenzoate, phthalate, isophthalate, terephthalate, salicylate,trifluoroacetate, monochloroacetate, dichloroacetate, trichloroacetate,fluoride, chloride, bromide, iodide, nitrate, chlorate, perchlorate,bromate, iodate, oxalate, malonate, methylmalonate, ethylmalonate,propylmalonate, butylmalonate, dimethylmalonate, diethylmalonate,succinate, methylsuccinate, glutarate, adipate, itaconate, maleate,fumarate, citraconate, citrate, and carbonate ions.

Specifically, suitable sulfonium compounds include triphenylsulfoniumformate, triphenylsulfonium acetate, triphenylsulfonium propionate,triphenylsulfonium butanoate, triphenylsulfonium pentanoate,triphenylsulfonium hexanoate, triphenylsulfonium heptanoate,triphenylsulfonium octanoate, triphenylsulfonium nonanoate,triphenylsulfonium decanoate, triphenylsulfonium oleate,triphenylsulfonium stearate, triphenylsulfonium linoleate,triphenylsulfonium linolenate, triphenylsulfonium benzoate,triphenylsulfonium p-methylbenzoate, triphenylsulfoniump-t-butylbenzoate, triphenylsulfonium phthalate, triphenylsulfoniumisophthalate, triphenylsulfonium terephthalate, triphenylsulfoniumsalicylate, triphenylsulfonium trifluoroacetate, triphenylsulfoniummonochloroacetate, triphenylsulfonium dichloroacetate,triphenylsulfonium trichloroacetate, triphenylsulfonium hydroxide,triphenylsulfonium oxalate, triphenylsulfonium malonate,triphenylsulfonium methylmalonate, triphenylsulfonium ethylmalonate,triphenylsulfonium propylmalonate, triphenylsulfonium butylmalonate,triphenylsulfonium dimethylmalonate, triphenylsulfonium diethylmalonate,triphenylsulfonium succinate, triphenylsulfonium methylsuccinate,triphenylsulfonium glutarate, triphenylsulfonium adipate,triphenylsulfonium itaconate, triphenylsulfonium maleate,triphenylsulfonium fumarate, triphenylsulfonium citraconate,triphenylsulfonium citrate, triphenylsulfonium carbonate,triphenylsulfonium chloride, triphenylsulfonium bromide,triphenylsulfonium iodide, triphenylsulfonium nitrate,triphenylsulfonium chlorate, triphenylsulfonium perchlorate,triphenylsulfonium bromate, triphenylsulfonium iodate,bistriphenylsulfonium oxalate, bistriphenylsulfonium malonate,bistriphenylsulfonium methylmalonate, bistriphenylsulfoniumethylmalonate, bistriphenylsulfonium propylmalonate,bistriphenylsulfonium butylmalonate, bistriphenylsulfoniumdimethylmalonate, bistriphenylsulfonium diethylmalonate,bistriphenylsulfonium succinate, bistriphenylsulfonium methylsuccinate,bistriphenylsulfonium glutarate, bistriphenylsulfonium adipate,bistriphenylsulfonium itaconate, bistriphenylsulfonium maleate,bistriphenylsulfonium fumarate, bistriphenylsulfonium citraconate,bistriphenylsulfonium citrate, and bistriphenylsulfonium carbonate.

Suitable iodonium compounds include diphenyliodonium formate,diphenyliodonium acetate, diphenyliodonium propionate, diphenyliodoniumbutanoate, diphenyliodonium pentanoate, diphenyliodonium hexanoate,diphenyliodonium heptanoate, diphenyliodonium octanoate,diphenyliodonium nonanoate, diphenyliodonium decanoate, diphenyliodoniumoleate, diphenyliodonium stearate, diphenyliodonium linoleate,diphenyliodonium linolenate, diphenyliodonium benzoate, diphenyliodoniump-methylbenzoate, diphenyliodonium p-t-butylbenzoate, diphenyliodoniumphthalate, diphenyliodonium isophthalate, diphenyliodoniumterephthalate, diphenyliodonium salicylate, diphenyliodoniumtrifluoroacetate, diphenyliodonium monochloroacetate, diphenyliodoniumdichloroacetate, diphenyliodonium trichloroacetate, diphenyliodoniumhydroxide, diphenyliodonium oxalate, diphenyliodonium malonate,diphenyliodonium methylmalonate, diphenyliodonium ethylmalonate,diphenyliodonium propylmalonate, diphenyliodonium butylmalonate,diphenyliodonium dimethylmalonate, diphenyliodonium diethylmalonate,diphenyliodonium succinate, diphenyliodonium methylsuccinate,diphenyliodonium glutarate, diphenyliodonium adipate, diphenyliodoniumitaconate, diphenyliodonium maleate, diphenyliodonium fumarate,diphenyliodonium citraconate, diphenyliodonium citrate, diphenyliodoniumcarbonate, diphenyliodonium chloride, diphenyliodonium bromide,diphenyliodonium iodide, diphenyliodonium nitrate, diphenyliodoniumchlorate, diphenyliodonium perchlorate, diphenyliodonium bromate,diphenyliodonium iodate, bisdiphenyliodonium oxalate,bisdiphenyliodonium malonate, bisdiphenyliodonium methylmalonate,bisdiphenyliodonium ethylmalonate, bisdiphenyliodonium propylmalonate,bisdiphenyliodonium butylmalonate, bisdiphenyliodonium dimethylmalonate,bisdiphenyliodonium diethylmalonate, bisdiphenyliodonium succinate,bisdiphenyliodonium methylsuccinate, bisdiphenyliodonium glutarate,bisdiphenyliodonium adipate, bisdiphenyliodonium itaconate,bisdiphenyliodonium maleate, bisdiphenyliodonium fumarate,bisdiphenyliodonium citraconate, bisdiphenyliodonium citrate, andbisdiphenyliodonium carbonate.

Suitable ammonium compounds include tetramethylammonium formate,tetramethylammonium acetate, tetramethylammonium propionate,tetramethylammonium butanoate, tetramethylammonium pentanoate,tetramethylammonium hexanoate, tetramethylammonium heptanoate,tetramethylammonium octanoate, tetramethylammonium nonanoate,tetramethylammonium decanoate, tetramethylammonium oleate,tetramethylammonium stearate, tetramethylammonium linoleate,tetramethylammonium linolenate, tetramethylammonium benzoate,tetramethylammonium p-methylbenzoate, tetramethylammoniump-t-butylbenzoate, tetramethylammonium phthalate, tetramethylammoniumisophthalate, tetramethylammonium terephthalate, tetramethylammoniumsalicylate, tetramethylammonium trifluoroacetate, tetramethylammoniummonochloroacetate, tetramethylammonium dichloroacetate,tetramethylammonium trichloroacetate, tetramethylammonium hydroxide,tetramethylammonium oxalate, tetramethylammonium malonate,tetramethylammonium methylmalonate, tetramethylammonium ethylmalonate,tetramethylammonium propylmalonate, tetramethylammonium butylmalonate,tetramethylammonium dimethylmalonate, tetramethylammoniumdiethylmalonate, tetramethylammonium succinate, tetramethylammoniummethylsuccinate, tetramethylammonium glutarate, tetramethylammoniumadipate, tetramethylammonium itaconate, tetramethylammonium maleate,tetramethylammonium fumarate, tetramethylammonium citraconate,tetramethylammonium citrate, tetramethylammonium carbonate,tetramethylammonium chloride, tetramethylammonium bromide,tetramethylammonium iodide, tetramethylammonium nitrate,tetramethylammonium chlorate, tetramethylammonium perchlorate,tetramethylammonium bromate, tetramethylammonium iodate,bistetramethylammonium oxalate, bistetramethylammonium malonate,bistetramethylammonium methylmalonate, bistetramethylammoniumethylmalonate, bistetramethylammonium propylmalonate,bistetramethylammonium butylmalonate, bistetramethylammoniumdimethylmalonate, bistetramethylammonium diethylmalonate,bistetramethylammonium succinate, bistetramethylammoniummethylsuccinate, bistetramethylammonium glutarate,bistetramethylammonium adipate, bistetramethylammonium itaconate,bistetramethylammonium maleate, bistetramethylammonium fumarate,bistetramethylammonium citraconate, bistetramethylammonium citrate,bistetramethylammonium carbonate; tetrapropylammonium formate,tetrapropylammonium acetate, tetrapropylammonium propionate,tetrapropylammonium butanoate, tetrapropylammonium pentanoate,tetrapropylammonium hexanoate, tetrapropylammonium heptanoate,tetrapropylammonium octanoate, tetrapropylammonium nonanoate,tetrapropylammonium decanoate, tetrapropylammonium oleate,tetrapropylammonium stearate, tetrapropylammonium linoleate,tetrapropylammonium linolenate, tetrapropylammonium benzoate,tetrapropylammonium p-methylbenzoate, tetrapropylammoniump-t-butylbenzoate, tetrapropylammonium phthalate, tetrapropylammoniumisophthalate, tetrapropylammonium terephthalate, tetrapropylammoniumsalicylate, tetrapropylammonium trifluoroacetate, tetrapropylammoniummonochloroacetate, tetrapropylammonium dichloroacetate,tetrapropylammonium trichloroacetate, tetrapropylammonium hydroxide,tetrapropylammonium oxalate, tetrapropylammonium malonate,tetrapropylammonium methylmalonate, tetrapropylammonium ethylmalonate,tetrapropylammonium propylmalonate, tetrapropylammonium butylmalonate,tetrapropylammonium dimethylmalonate, tetrapropylammoniumdiethylmalonate, tetrapropylammonium succinate, tetrapropylammoniummethylsuccinate, tetrapropylammonium glutarate, tetrapropylammoniumadipate, tetrapropylammonium itaconate, tetrapropylammonium maleate,tetrapropylammonium fumarate, tetrapropylammonium citraconate,tetrapropylammonium citrate, tetrapropylammonium carbonate,tetrapropylammonium chloride, tetrapropylammonium bromide,tetrapropylammonium iodide, tetrapropylammonium nitrate,tetrapropylammonium chlorate, tetrapropylammonium perchlorate,tetrapropylammonium bromate, tetrapropylammonium iodate,bistetrapropylammonium oxalate, bistetrapropylammonium malonate,bistetrapropylammonium methylmalonate, bistetrapropylammoniumethylmalonate, bistetrapropylammonium propylmalonate,bistetrapropylammonium butylmalonate, bistetrapropylammoniumdimethylmalonate, bistetrapropylammonium diethylmalonate,bistetrapropylammonium succinate, bistetrapropylammoniummethylsuccinate, bistetrapropylammonium glutarate,bistetrapropylammonium adipate, bistetrapropylammonium itaconate,bistetrapropylammonium maleate, bistetrapropylammonium fumarate,bistetrapropylammonium citraconate, bistetrapropylammonium citrate,bistetrapropylammonium carbonate; and tetrabutylammonium formate,tetrabutylammonium acetate, tetrabutylammonium propionate,tetrabutylammonium butanoate, tetrabutylammonium pentanoate,tetrabutylammonium hexanoate, tetrabutylammonium heptanoate,tetrabutylammonium octanoate, tetrabutylammonium nonanoate,tetrabutylammonium decanoate, tetrabutylammonium oleate,tetrabutylammonium stearate, tetrabutylammonium linoleate,tetrabutylammonium linolenate, tetrabutylammonium benzoate,tetrabutylammonium p-methylbenzoate, tetrabutylammoniump-t-butylbenzoate, tetrabutylammonium phthalate, tetrabutylammoniumisophthalate, tetrabutylammonium terephthalate, tetrabutylammoniumsalicylate, tetrabutylammonium trifluoroacetate, tetrabutylammoniummonochloroacetate, tetrabutylammonium dichloroacetate,tetrabutylammonium trichloroacetate, tetrabutylammonium hydroxide,tetrabutylammonium oxalate, tetrabutylammonium malonate,tetrabutylammonium methylmalonate, tetrabutylammonium ethylmalonate,tetrabutylammonium propylmalonate, tetrabutylammonium butylmalonate,tetrabutylammonium dimethylmalonate, tetrabutylammonium diethylmalonate,tetrabutylammonium succinate, tetrabutylammonium methylsuccinate,tetrabutylammonium glutarate, tetrabutylammonium adipate,tetrabutylammonium itaconate, tetrabutylammonium maleate,tetrabutylammonium fumarate, tetrabutylammonium citraconate,tetrabutylammonium citrate, tetrabutylammonium carbonate,tetrabutylammonium chloride, tetrabutylammonium bromide,tetrabutylammonium iodide, tetrabutylammonium nitrate,tetrabutylammonium chlorate, tetrabutylammonium perchlorate,tetrabutylammonium bromate, tetrabutylammonium iodate,bistetrabutylammonium oxalate, bistetrabutylammonium malonate,bistetrabutylammonium methylmalonate, bistetrabutylammoniumethylmalonate, bistetrabutylammonium propylmalonate,bistetrabutylammonium butylmalonate, bistetrabutylammoniumdimethylmalonate, bistetrabutylammonium diethylmalonate,bistetrabutylammonium succinate, bistetrabutylammonium methylsuccinate,bistetrabutylammonium glutarate, bistetrabutylammonium adipate,bistetrabutylammonium itaconate, bistetrabutylammonium maleate,bistetrabutylammonium fumarate, bistetrabutylammonium citraconate,bistetrabutylammonium citrate, and bistetrabutylammonium carbonate.

The thermal crosslink accelerators may be used alone or in admixture oftwo or more. An appropriate amount of the thermal crosslink acceleratoradded is 0.01 to 50 parts, more preferably 0.1 to 40 parts by weight per100 parts by weight of the base polymer, that is, the silicon-containingcompound obtained by the above-described method.

To establish stability, a mono or polyfunctional organic acid of 1 to 30carbon atoms must be added to the heat-curable silicon-containingfilm-forming composition as component (C). Suitable organic acidsinclude, but are not limited to, formic acid, acetic acid, propionicacid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid,octanoic acid, nonanoic acid, decanoic acid, oleic acid, stearic acid,linoleic acid, linolenic acid, benzoic acid, phthalic acid, isophthalicacid, terephthalic acid, salicylic acid, trifluoroacetic acid,monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, oxalicacid, malonic acid, methylmalonic acid, ethylmalonic acid, propylmalonicacid, butylmalonic acid, dimethylmalonic acid, diethylmalonic acid,succinic acid, methylsuccinic acid, glutaric acid, adipic acid, itaconicacid, maleic acid, fumaric acid, citraconic acid, and citric acid. Ofthese, oxalic acid, maleic acid, formic acid, acetic acid, propionicacid, and citric acid are preferred. A mixture of two or more acids maybe used to maintain the stability.

The amount of the acid added is 0.001 to 25 parts, preferably 0.01 to 15parts, and more preferably 0.1 to 5 parts by weight per 100 parts byweight of the silicon-containing compound (A) in the composition.Alternatively, the organic acid is added in such amounts that thecomposition may be at a proper pH, preferably 0≦pH≦7, more preferably0.3≦pH≦6.5, and even more preferably 0.5≦pH≦6.

According to the invention, a mono or polyhydric alcohol substitutedwith a cyclic ether is added as a stabilizer (D) to thesilicon-containing film-forming composition so that the composition isfurther improved in stability. Specifically suitable alcohols includeether compounds having the structure shown below.

Herein R^(90a) is hydrogen, a straight, branched or cyclic monovalenthydrocarbon group of 1 to 10 carbon atoms,R⁹¹O—(CH₂CH₂O)_(n1)—(CH₂)_(n2)— (wherein R⁹¹ is hydrogen or methyl,0≦n1≦5, 0≦n2≦3), or R⁹²O—[CH(CH₃)CH₂O]_(n3)—(CH₂)_(n4)— (wherein R⁹² ishydrogen or methyl, 0≦n3≦5, 0≦n4≦3). R^(90b) is hydroxyl, a straight,branched or cyclic monovalent hydrocarbon group of 1 to 10 carbon atomshaving at least one hydroxyl group, HO—(CH₂CH₂O)_(n5)—(CH₂)_(n6)-(wherein 1≦n5≦5, 1≦n6≦3), orHO—[CH(CH₃)CH₂O]_(n7)—(CH₂)_(n8)— (wherein 1≦n7≦5, 1≦n8≦3).

The stabilizer may be used alone or in admixture. An appropriate amountof the stabilizer added is 0.001 to 50 parts, and preferably 0.01 to 40parts by weight per 100 parts by weight of the base polymer orsilicon-containing compound (A). Stabilizers of the preferred structureinclude crown ether derivatives and compounds substituted with a bicycloring having an oxygen atom at the bridgehead. The addition of such astabilizer helps to keep the electric charge of acid more stable,contributing to further stabilization of the silicon-containing compoundin the composition.

In the composition comprising the silicon-containing compound accordingto the invention, an organic solvent is present as component (E). It maybe the same as used in the preparation of the silicon-containingcompound. Water-soluble organic solvents are preferred. Examples of thesolvent used include monoalkyl ethers of ethylene glycol, diethyleneglycol, triethylene glycol, etc. and monoalkyl ethers of propyleneglycol, dipropylene glycol, butane diol, pentane diol, etc. The organicsolvent is preferably selected from among butane diol monomethyl ether,propylene glycol monomethyl ether, ethylene glycol monomethyl ether,butane diol monoethyl ether, propylene glycol monoethyl ether, ethyleneglycol monoethyl ether, butane diol monopropyl ether, propylene glycolmonopropyl ether, and ethylene glycol monopropyl ether.

To the inventive composition, water may be added. The addition of watercauses the silicon-containing compound to be hydrated, ameliorating thelithography performance. The content of water is preferably from morethan 0% to less than 50%, more preferably from 0.3% to 30%, even morepreferably 0.5% to 20% by weight, based on the solvent component in thecomposition. Too high a water content may adversely affect theuniformity of a coated film and at the worst, cause cissing whereas toolow a water content may undesirably detract from lithographyperformance.

The total amount of solvents including water is preferably 500 to100,000 parts, more preferably 400 to 50,000 parts by weight per 100parts by weight of the base polymer.

In the composition, a photoacid generator may be used. Examples of thephotoacid generator which can be used herein include:

-   (A-i) onium salts of the formula (P1a-1), (P1a-2) or (P1b),-   (A-ii) diazomethane derivatives of the formula (P2),-   (A-iii) glyoxime derivatives of the formula (P3),-   (A-iv) bissulfone derivatives of the formula (P4),-   (A-v) sulfonic acid esters of N-hydroxyimide compounds of the    formula (P5),-   (A-vi) β-ketosulfonic acid derivatives,-   (A-vii) disulfone derivatives,-   (A-viii) nitrobenzylsulfonate derivatives, and-   (A-ix) sulfonate derivatives.

These photoacid generators are described in detail.

(i) Onium Salts of Formula (P1a-1), (P1a-2) or (P1b):

Herein, R^(101a), R^(101b), and R^(101c) independently representstraight, branched or cyclic alkyl, alkenyl, oxoalkyl or oxoalkenylgroups of 1 to 12 carbon atoms, aryl groups of 6 to 20 carbon atoms, oraralkyl or aryloxoalkyl groups of 7 to 12 carbon atoms, wherein some orall of the hydrogen atoms may be replaced by alkoxy or other groups.Also, R^(101b) and R^(101c), taken together, may form a ring. R^(101b)and R^(101c) each are alkylene groups of 1 to 6 carbon atoms when theyform a ring. K⁻ is a non-nucleophilic counter ion.

R^(101a), R^(101b), and R^(101c) may be the same or different and areillustrated below. Exemplary alkyl groups include methyl, ethyl, propyl,isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl,cyclopentyl, cyclohexyl, cycloheptyl, cyclopropylmethyl,4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl.Exemplary alkenyl groups include vinyl, allyl, propenyl, butenyl,hexenyl, and cyclohexenyl. Exemplary oxoalkyl groups include2-oxocyclopentyl and 2-oxocyclohexyl as well as 2-oxopropyl,2-cyclopentyl-2-oxoethyl, 2-cyclohexyl-2-oxoethyl, and2-(4-methylcyclohexyl)-2-oxoethyl. Exemplary aryl groups include phenyland naphthyl; alkoxyphenyl groups such as p-methoxyphenyl,m-methoxyphenyl, o-methoxyphenyl, ethoxyphenyl, p-tert-butoxyphenyl, andm-tert-butoxyphenyl; alkylphenyl groups such as 2-methylphenyl,3-methylphenyl, 4-methylphenyl, ethylphenyl, 4-tert-butylphenyl,4-butylphenyl, and dimethylphenyl; alkylnaphthyl groups such asmethylnaphthyl and ethylnaphthyl; alkoxynaphthyl groups such asmethoxynaphthyl and ethoxynaphthyl; dialkylnaphthyl groups such asdimethylnaphthyl and diethylnaphthyl; and dialkoxynaphthyl groups suchas dimethoxynaphthyl and diethoxynaphthyl. Exemplary aralkyl groupsinclude benzyl, phenylethyl, and phenethyl. Exemplary aryloxoalkylgroups are 2-aryl-2-oxoethyl groups such as 2-phenyl-2-oxoethyl,2-(1-naphthyl)-2-oxoethyl, and 2-(2-naphthyl)-2-oxoethyl. Examples ofthe non-nucleophilic counter ion represented by K⁻ includefluoroalkylsulfonate ions such as triflate,1,1,1-trifluoroethanesulfonate, and nonafluorobutanesulfonate,arylsulfonate ions such as tosylate, benzenesulfonate,4-fluorobenzenesulfonate, and 1,2,3,4,5-pentafluorobenzenesulfonate, andalkylsulfonate ions such as mesylate and butanesulfonate.

Herein, R^(102a) and R^(102b) independently represent straight, branchedor cyclic alkyl groups of 1 to 8 carbon atoms. R¹⁰³ represents astraight, branched or cyclic alkylene group of 1 to 10 carbon atoms.R^(104a) and R^(104b) independently represent 2-oxoalkyl groups of 3 to7 carbon atoms. K⁻ is a non-nucleophilic counter ion.

Illustrative of the groups represented by R^(102a) and R^(102b) aremethyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl,pentyl, hexyl, heptyl, octyl, cyclopentyl, cyclohexyl,cyclopropylmethyl, 4-methylcyclohexyl, and cyclohexylmethyl.Illustrative of the groups represented by R¹⁰³ are methylene, ethylene,propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene,1,4-cyclohexylene, 1,2-cyclohexylene, 1,3-cyclopentylene,1,4-cyclooctylene, and 1,4-cyclohexanedimethylene. Illustrative of thegroups represented by R^(104a) and R^(104b) are 2-oxopropyl,2-oxocyclopentyl, 2-oxocyclohexyl, and 2-oxocycloheptyl. Illustrativeexamples of the counter ion represented by K⁻ are the same asexemplified for formulae (P1a-1), (P1a-2) and (P1a-3).

(ii) Diazomethane Derivatives of Formula (P2)

Herein, R¹⁰⁵ and R¹⁰⁶ independently represent straight, branched orcyclic alkyl or halogenated alkyl groups of 1 to 12 carbon atoms,substituted or unsubstituted aryl or halogenated aryl groups of 6 to 20carbon atoms, or aralkyl groups of 7 to 12 carbon atoms.

Of the groups represented by R¹⁰⁵ and R¹⁰⁶, exemplary alkyl groupsinclude methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl,tert-butyl, pentyl, hexyl, heptyl, octyl, amyl, cyclopentyl, cyclohexyl,cycloheptyl, norbornyl, and adamantyl. Exemplary halogenated alkylgroups include trifluoromethyl, 1,1,1-trifluoroethyl,1,1,1-trichloroethyl, and nonafluorobutyl. Exemplary aryl groups includephenyl; alkoxyphenyl groups such as p-methoxyphenyl, m-methoxyphenyl,o-methoxyphenyl, ethoxyphenyl, p-tert-butoxyphenyl, andm-tert-butoxyphenyl; and alkylphenyl groups such as 2-methylphenyl,3-methylphenyl, 4-methylphenyl, ethylphenyl, 4-tert-butylphenyl,4-butylphenyl, and dimethylphenyl. Exemplary halogenated aryl groupsinclude fluorophenyl, chlorophenyl, and 1,2,3,4,5-pentafluorophenyl.Exemplary aralkyl groups include benzyl and phenethyl.

(iii) Glyoxime Derivatives of Formula (P3)

Herein, R¹⁰⁷, R¹⁰⁸, and R¹⁰⁹ independently represent straight, branchedor cyclic alkyl or halogenated alkyl groups of 1 to 12 carbon atoms,aryl or halogenated aryl groups of 6 to 20 carbon atoms, or aralkylgroups of 7 to 12 carbon atoms. Also, R¹⁰⁵ and R¹⁰⁹, taken together, mayform a ring. R¹⁰⁸ and R¹⁰⁹ each are straight or branched alkylene groupsof 1 to 6 carbon atoms when they form a ring.

Illustrative examples of the alkyl, halogenated alkyl, aryl, halogenatedaryl, and aralkyl groups represented by R¹⁰⁷, R¹⁰⁸, and R¹⁰⁹ are thesame as exemplified for R¹⁰⁵ and R¹⁰⁶. Examples of the alkylene groupsrepresented by R¹⁰⁵ and R¹⁰⁹ include methylene, ethylene, propylene,butylene, and hexylene.

(iv) Bissulfone Derivatives of Formula (P4)

Herein, R^(101a) and R^(101b) are as defined above.

(v) Sulfonic Acid Esters of N-hydroxyimide Compounds of Formula (P5)

Herein, R¹¹⁰ is an arylene group of 6 to 10 carbon atoms, alkylene groupof 1 to 6 carbon atoms, or alkenylene group of 2 to 6 carbon atomswherein some or all of the hydrogen atoms may be replaced by straight orbranched alkyl or alkoxy groups of 1 to 4 carbon atoms, nitro, acetyl,or phenyl groups. R¹¹¹ is a straight, branched or cyclic alkyl group of1 to 8 carbon atoms, alkenyl, alkoxyalkyl, phenyl or naphthyl groupwherein some or all of the hydrogen atoms may be replaced by alkyl oralkoxy groups of 1 to 4 carbon atoms, phenyl groups (which may havesubstituted thereon an alkyl or alkoxy of 1 to 4 carbon atoms, nitro, oracetyl group), hetero-aromatic groups of 3 to 5 carbon atoms, orchlorine or fluorine atoms.

Of the groups represented by R¹¹⁰, exemplary arylene groups include1,2-phenylene and 1,8-naphthylene; exemplary alkylene groups includemethylene, ethylene, trimethylene, tetramethylene, phenylethylene, andnorbornane-2,3-diyl; and exemplary alkenylene groups include1,2-vinylene, 1-phenyl-1,2-vinylene, and 5-norbornene-2,3-diyl. Of thegroups represented by R¹¹¹, exemplary alkyl groups are as exemplifiedfor R^(101a) to R^(101o); exemplary alkenyl groups include vinyl,1-propenyl, allyl, 1-butenyl, 3-butenyl, isoprenyl, 1-pentenyl,3-pentenyl, 4-pentenyl, dimethylallyl, 1-hexenyl, 3-hexenyl, 5-hexenyl,1-heptenyl, 3-heptenyl, 6-heptenyl, and 7-octenyl; and exemplaryalkoxyalkyl groups include methoxymethyl, ethoxymethyl, propoxymethyl,butoxymethyl, pentyloxymethyl, hexyloxymethyl, heptyloxymethyl,methoxyethyl, ethoxyethyl, propoxyethyl, butoxyethyl, pentyloxyethyl,hexyloxyethyl, methoxypropyl, ethoxypropyl, propoxypropyl, butoxypropyl,methoxybutyl, ethoxybutyl, propoxybutyl, methoxypentyl, ethoxypentyl,methoxyhexyl, and methoxyheptyl.

Of the substituents on these groups, the alkyl groups of 1 to 4 carbonatoms include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl andtert-butyl; and the alkoxy groups of 1 to 4 carbon atoms includemethoxy, ethoxy, propoxy, isopropoxy, n-butoxy, isobutoxy, andtert-butoxy. The phenyl groups which may have substituted thereon analkyl or alkoxy of 1 to 4 carbon atoms, nitro, or acetyl group includephenyl, tolyl, p-tert-butoxyphenyl, p-acetylphenyl and p-nitrophenyl.The hetero-aromatic groups of 3 to 5 carbon atoms include pyridyl andfuryl.

Illustrative examples of the photoacid generator include:

onium salts such as diphenyliodonium trifluoromethanesulfonate,(p-tert-butoxyphenyl)phenyliodonium trifluoromethanesulfonate,diphenyliodonium p-toluenesulfonate, (p-tert-butoxyphenyl)phenyliodoniump-toluenesulfonate, triphenylsulfonium trifluoromethanesulfonate,(p-tert-butoxyphenyl)diphenylsulfonium trifluoromethane-sulfonate,bis(p-tert-butoxyphenyl)phenylsulfonium trifluoromethane-sulfonate,tris(p-tert-butoxyphenyl)sulfonium trifluoromethanesulfonate,triphenylsulfonium p-toluenesulfonate,(p-tert-butoxyphenyl)diphenylsulfonium p-toluenesulfonate,bis(p-tert-butoxyphenyl)phenylsulfonium p-toluenesulfonate,tris(p-tert-butoxyphenyl)sulfonium p-toluenesulfonate,triphenylsulfonium nonafluorobutanesulfonate, triphenylsulfoniumbutanesulfonate, trimethylsulfonium trifluoromethanesulfonate,trimethylsulfonium p-toluenesulfonate,cyclohexylmethyl(2-oxocyclohexyl)sulfonium trifluoromethane-sulfonate,cyclohexylmethyl(2-oxocyclohexyl)sulfonium p-toluenesulfonate,dimethylphenylsulfonium trifluoromethanesulfonate,dimethylphenylsulfonium p-toluenesulfonate, dicyclohexylphenylsulfoniumtrifluoromethanesulfonate, dicyclohexylphenylsulfoniump-toluenesulfonate, trinaphthylsulfonium trifluoromethanesulfonate,cyclohexylmethyl(2-oxocyclohexyl)sulfonium trifluoromethane-sulfonate,(2-norbornyl)methyl(2-oxocyclohexyl)sulfoniumtrifluoro-methanesulfonate,ethylenebis[methyl(2-oxocyclopentyl)sulfoniumtrifluoro-methanesulfonate], and1,2′-naphthylcarbonylmethyltetrahydrothiophenium triflate;

diazomethane derivatives such as bis(benzenesulfonyl)diazomethane,bis(p-toluenesulfonyl)diazomethane, bis(xylenesulfonyl)diazomethane,bis(cyclohexylsulfonyl)diazomethane,bis(cyclopentylsulfonyl)diazomethane, bis(n-butylsulfonyl)diazomethane,bis(isobutylsulfonyl)diazomethane, bis(sec-butylsulfonyl)diazomethane,bis(n-propylsulfonyl)diazomethane, bis(isopropylsulfonyl)diazomethane,bis(tert-butylsulfonyl)diazomethane, bis(n-amylsulfonyl)diazomethane,bis(isoamylsulfonyl)diazomethane, bis(sec-amylsulfonyl)diazomethane,bis(tert-amylsulfonyl)diazomethane,1-cyclohexylsulfonyl-1-(tert-butylsulfonyl)diazomethane,1-cyclohexylsulfonyl-1-(tert-amylsulfonyl)diazomethane, and1-tert-amylsulfonyl-1-(tert-butylsulfonyl)diazomethane;

glyoxime derivatives such asbis-O-(p-toluenesulfonyl)-α-dimethylglyoxime,bis-O-(p-toluenesulfonyl)-α-diphenylglyoxime,bis-O-(p-toluenesulfonyl)-α-dicyclohexylglyoxime,bis-O-(p-toluenesulfonyl)-2,3-pentanedioneglyoxime,bis-O-(p-toluenesulfonyl)-2-methyl-3,4-pentanedioneglyoxime,bis-O-(n-butanesulfonyl)-α-dimethylglyoxime,bis-O-(n-butanesulfonyl)-α-diphenylglyoxime,bis-O-(n-butanesulfonyl)-α-dicyclohexylglyoxime,bis-O-(n-butanesulfonyl)-2,3-pentanedioneglyoxime,bis-O-(n-butanesulfonyl)-2-methyl-3,4-pentanedioneglyoxime,bis-O-(methanesulfonyl)-α-dimethylglyoxime,bis-O-(trifluoromethanesulfonyl)-α-dimethylglyoxime,bis-O-(1,1,1-trifluoroethanesulfonyl)-α-dimethylglyoxime,bis-O-(tert-butanesulfonyl)-α-dimethylglyoxime,bis-O-(perfluorooctanesulfonyl)-α-dimethylglyoxime,bis-O-(cyclohexanesulfonyl)-α-dimethylglyoxime,bis-O-(benzenesulfonyl)-α-dimethylglyoxime,bis-O-(p-fluorobenzenesulfonyl)-α-dimethylglyoxime,bis-O-(p-tert-butylbenzenesulfonyl)-α-dimethylglyoxime,bis-O-(xylenesulfonyl)-α-dimethylglyoxime, andbis-O-(camphorsulfonyl)-α-dimethylglyoxime;

bissulfone derivatives such as bisnaphthylsulfonylmethane,bistrifluoromethylsulfonylmethane, bismethylsulfonylmethane,bisethylsulfonylmethane, bispropylsulfonylmethane,bisisopropylsulfonylmethane, bis-p-toluenesulfonylmethane, andbisbenzenesulfonylmethane;

β-ketosulfonic acid derivatives such as2-cyclohexylcarbonyl-2-(p-toluenesulfonyl)propane and2-isopropylcarbonyl-2-(p-toluenesulfonyl)propane;

disulfone derivatives such as diphenyl disulfone and dicyclohexyldisulfone:

nitrobenzyl sulfonate derivatives such as 2,6-dinitrobenzylp-toluenesulfonate and 2,4-dinitrobenzyl p-toluenesulfonate;

sulfonic acid ester derivatives such as1,2,3-tris(methanesulfonyloxy)benzene,1,2,3-tris(trifluoromethanesulfonyloxy)benzene, and1,2,3-tris(p-toluenesulfonyloxy)benzene; and

sulfonic acid esters of N-hydroxyimides such as N-hydroxysuccinimidemethanesulfonate, N-hydroxysuccinimide trifluoromethanesulfonate,N-hydroxysuccinimide ethanesulfonate, N-hydroxysuccinimide1-propanesulfonate, N-hydroxysuccinimide 2-propanesulfonate,N-hydroxysuccinimide 1-pentanesulfonate, N-hydroxysuccinimide1-octanesulfonate, N-hydroxysuccinimide p-toluenesulfonate,N-hydroxysuccinimide p-methoxybenzenesulfonate, N-hydroxysuccinimide2-chloroethanesulfonate, N-hydroxysuccinimide benzenesulfonate,N-hydroxysuccinimide 2,4,6-trimethylbenzenesulfonate,N-hydroxysuccinimide 1-naphthalenesulfonate, N-hydroxysuccinimide2-naphthalenesulfonate, N-hydroxy-2-phenylsuccinimide methanesulfonate,N-hydroxymaleimide methanesulfonate, N-hydroxymaleimide ethanesulfonate,N-hydroxy-2-phenylmaleimide methanesulfonate, N-hydroxyglutarimidemethanesulfonate, N-hydroxyglutarimide benzenesulfonate,N-hydroxyphthalimide methanesulfonate, N-hydroxyphthalimidebenzenesulfonate, N-hydroxyphthalimide trifluoromethanesulfonate,N-hydroxyphthalimide p-toluenesulfonate, N-hydroxynaphthalimidemethanesulfonate, N-hydroxynaphthalimide benzenesulfonate,N-hydroxy-5-norbornene-2,3-dicarboxyimide methanesulfonate,N-hydroxy-5-norbornene-2,3-dicarboxyimide trifluoromethane-sulfonate,and N-hydroxy-5-norbornene-2,3-dicarboxyimide p-toluenesulfonate.

Preferred among these photoacid generators are onium salts such astriphenylsulfonium trifluoromethanesulfonate,(p-tert-butoxyphenyl)diphenylsulfonium trifluoromethane-sulfonate,tris(p-tert-butoxyphenyl)sulfonium trifluoromethanesulfonate,triphenylsulfonium p-toluenesulfonate,(p-tert-butoxyphenyl)diphenylsulfonium p-toluenesulfonate,tris(p-tert-butoxyphenyl)sulfonium p-toluenesulfonate,trinaphthylsulfonium trifluoromethanesulfonate,cyclohexylmethyl(2-oxocyclohexyl)sulfonium trifluoromethane-sulfonate,(2-norbornyl)methyl(2-oxocylohexyl)sulfonium trifluoro-methanesulfonate,and 1,2′-naphthylcarbonylmethyltetrahydrothiophenium triflate;diazomethane derivatives such as bis(benzenesulfonyl)diazomethane,bis(p-toluenesulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane,bis(n-butylsulfonyl)diazomethane, bis(isobutylsulfonyl)diazomethane,bis(sec-butylsulfonyl)diazomethane, bis(n-propylsulfonyl)diazomethane,bis(isopropylsulfonyl)diazomethane, andbis(tert-butylsulfonyl)diazomethane; glyoxime derivatives such asbis-O-(p-toluenesulfonyl)-α-dimethylglyoxime andbis-O-(n-butanesulfonyl)-α-dimethylglyoxime; bissulfone derivatives suchas bisnaphthylsulfonylmethane; and sulfonic acid esters ofN-hydroxyimide compounds such as N-hydroxysuccinimide methanesulfonate,N-hydroxysuccinimide trifluoromethanesulfonate, N-hydroxysuccinimide1-propanesulfonate, N-hydroxysuccinimide 2-propanesulfonate,N-hydroxysuccinimide 1-pentanesulfonate, N-hydroxysuccinimidep-toluenesulfonate, N-hydroxynaphthalimide methanesulfonate, andN-hydroxynaphthalimide benzenesulfonate.

These photoacid generators may be used singly or in combinations of twoor more thereof. An appropriate amount of the photoacid generator addedis 0.01 to 50 parts, and more preferably 0.05 to 40 parts by weight, per100 parts by weight of the base polymer, that is, the silicon-containingcompound (A) obtained by the above-described method.

In the composition, a surfactant may optionally be compounded. Thepreferred surfactants are nonionic surfactants, for example,perfluoroalkyl polyoxyethylene ethanols, fluorinated alkyl esters,perfluoroalkylamine oxides, perfluoroalkyl ethylene oxide adducts, andfluorinated organosiloxanes. They are commercially available, forexample, under the trade name of Fluorad FC-430, FC-431 and FC-4430(Sumitomo 3M Co., Ltd.), Surflon S-141, S-145, KH-10, KH-20, KH-30 andKH-40 (Asahi Glass Co., Ltd.), Unidyne DS-401, DS-403 and DS-451 (DaikinIndustries Ltd.), Megaface F-8151 (Dai-Nippon Ink & Chemicals, Inc.),X-70-092 and X-70-093 (Shin-Etsu Chemical Co., Ltd.). Inter alia,Fluorad FC-4430, KH-20, KH-30, and X-70-093 are preferred.

The surfactant is added to the composition in an ordinary amount as longas the objects of the invention are not compromised, preferably in anamount of 0 to 10 parts, more preferably 0 to 5 parts by weight, per 100parts by weight of the base polymer.

A silicon-containing film useful as an etching mask can be formed on asubstrate from the silicon-containing film forming composition of theinvention by spin coating or similar techniques, as is the photoresistfilm. After spin coating, the coating is desirably baked to evaporateoff the solvent and to promote crosslinking reaction for preventing thecoating from mixing with the overlying resist film. The baking step ispreferably effected at a temperature of 50 to 500° C. for a time of 10to 300 seconds. While the preferred temperature range varies dependingon the structure of a device to be manufactured, it is typically equalto or lower than 400° C. in order to minimize thermal damage to thedevice.

According to the invention, a pattern can be formed by forming asilicon-containing film, as described above, on a processable portion ofa processable substrate via an intervening undercoat film, and forming aphotoresist film on the silicon-containing film. The processable portionof a processable substrate may be a low-dielectric constant insulatingfilm having a k value of up to 3, a primarily processed low-dielectricconstant insulating film, a nitrogen and/or oxygen-containing inorganicfilm, a metal film or the like.

More specifically, the processable substrate (i.e., substrate to beprocessed or patterned) may be a processable layer or portion formed ona base substrate. The base substrate is not particularly limited and maybe made of any material which is selected from Si, amorphous silicon(α-Si), polycrystalline silicon (p-Si), SiO₂, SiN, SiON, W, TiN, Al,etc, but different from the processable layer. The processable layer maybe any of films of Si, SiO₂, SiN, SiON, p-Si, α-Si, W, W—Si, Al, Cu,Al—Si, etc., and various low dielectric films and etching stop filmsthereof and generally has a thickness of 50 to 10,000 nm, preferably 100to 5,000 nm.

In a further embodiment, an antireflective coating (ARC) may be formedbetween the silicon-containing film and the overcoat resist film using acommercially available ARC material. Usually the ARC is formed of acompound having an aromatic substituent group. The ARC must be selectedso as to impose little or no etching load to the overcoat resist filmwhen the pattern of the overcoat resist film is transferred by dryetching. For example, if the thickness of the ARC is equal to or lessthan 80%, preferably equal to or less than 50% of the thickness of theovercoat resist film, the load applied during dry etching is minimized.In this embodiment, the ARC is preferably adjusted to a minimumreflectance equal to or less than 2%, more preferably equal to or lessthan 1%, and even more preferably equal to or less than 0.5%.

When the silicon-containing film of the invention is used in theexposure process using ArF excimer laser radiation, the overcoat resistfilm may be any of ordinary ArF excimer laser lithography resistcompositions. There are known a number of candidates for the ArF excimerlaser lithography resist composition, including resist compositions ofthe positive working type primarily comprising a polymer which becomessoluble in an alkaline aqueous solution as a result of decomposition ofacid labile groups under the action of an acid, a photoacid generator,and a basic compound for controlling acid diffusion; and resistcompositions of the negative working type primarily comprising a polymerwhich becomes insoluble in an alkaline aqueous solution as a result ofreaction with a crosslinker under the action of an acid, a photoacidgenerator, a crosslinker, and a basic compound for controlling aciddiffusion. Properties of a resist composition differ depending on whattype of polymer is used. Well-known polymers are generally classifiedinto poly(meth)acrylic, cycloolefin/maleic anhydride (COMA) copolymer,COMA-(meth)acrylic hybrid, ring-opening metathesis polymerization(ROMP), and polynorbornene systems. Of these, a resist compositioncomprising a poly(meth)acrylic polymer has superior resolution to otherpolymers because etching resistance is achieved by introducing analicyclic skeleton into side chain.

There are known a number of ArF excimer laser lithography resistcompositions comprising poly(meth)acrylic polymers. For the positivetype, a polymer is composed of a combination of units for providing themain function of etching resistance, units which turn to be alkalisoluble as a result of decomposition under the action of an acid, andunits for providing adhesion, or in some cases, a combination comprisingone unit capable of providing two or more of the above-mentionedfunctions. As the unit which changes alkali solubility under the actionof an acid, (meth)acrylic acid esters having an acid labile group withan adamantane skeleton (see JP-A 9-73173) and (meth)acrylic acid estershaving an acid labile group with a norbornane or tetracyclododecaneskeleton (see JP-A 2003-84438) are advantageously used because theyprovide high resolution and etching resistance. As the unit whichensures adhesion, (meth)acrylic acid esters having a norbornane sidechain with a lactone ring (see WO 00/01684), (meth)acrylic acid estershaving an oxanorbornane side chain (see JP-A 2000-159758), and(meth)acrylic acid esters having a hydroxyadamantyl side chain (see JP-A8-12626) are advantageously used because they provide satisfactoryetching resistance and high resolution. Further, a polymer comprisingunits having as a functional group an alcohol which exhibits acidity byfluorine substitution on the vicinal carbon (see Polym. Mater. Sci.Eng., 1997, 77, pp 449) draws attention as a resist polymer complyingwith the immersion lithography of the current great interest because theunits impart anti-swelling physical properties and hence, highresolution to the polymer. However, a decline of etching resistance dueto inclusion of fluorine within the polymer is a problem. Thesilicon-containing film (for etching mask) of the invention isadvantageously used in combination with such an organic resist materialwhich is relatively difficult to secure etching resistance.

In the ArF excimer laser lithography resist compositions comprising theabove-described polymers, acid generators, basic compounds and othercomponents are also included. The acid generators used herein may besubstantially the same as those used in the silicon-containing filmforming composition of the invention, with onium salts being especiallypreferred for sensitivity and resolution. Also a number of basiccompounds are known, and a choice may be advantageously made among thebasic compounds described in JP-A 2005-146252 (US 2005/106499A1), forexample.

After the silicon-containing film (for etching mask) is formed, aphotoresist layer is formed thereon using a photoresist compositionsolution. Like the silicon-containing film (for etching mask), thephotoresist composition solution is preferably applied by spin coating.Once the resist composition is spin coated, it is prebaked, preferablyat 80 to 180° C. for 10 to 300 seconds. The coating is then exposed,followed by post-exposure bake (PEB) and development, yielding a resistpattern.

The silicon-containing film (for etching mask) is etched using afluorocarbon gas, nitrogen gas, carbon dioxide gas or the like. Withthese gases, the silicon-containing film (for etching mask) is etched atso high an etching rate that the overcoat resist film undergoes lessslimming.

In the multilayer resist process using the silicon-containing film ofthe invention, an undercoat film is provided between thesilicon-containing film and the processable substrate. When theundercoat film is used as an etching mask for the processable substrate,the undercoat film is preferably an organic film having an aromaticframework. When the undercoat film is a sacrificial film, it may beeither an organic film or a silicon-containing material having a siliconcontent equal to or less than 15% by weight.

It is noted that the organic film having an aromatic framework may beformed of any material selected from a number of well-known resistundercoat materials. A number of resins including4,4′-(9H-fluoren-9-ylidene)bisphenol novolac resin with a molecularweight of 11,000 as described in JP-A 2005-128509 and other novolacresins are known as the resist undercoat film material for the bi- ortrilayer resist process, and any of them can be used herein. If it isdesired to enhance heat resistance beyond ordinary novolac resins, it isacceptable to incorporate polycyclic frameworks as in4,4′-(9H-fluoren-9-ylidene)bisphenol novolac resins or to selectpolyimide resins (e.g., JP-A 2004-153125).

In the multilayer resist process using as the undercoat film an organicfilm which can serve as an etching mask for the processable substrate,the organic film is used in a process involving transferring the resistpattern resulting from previous pattern formation to thesilicon-containing film and transferring again the pattern ofsilicon-containing film to the organic film, and specifically, in thesecond transfer step. Then the organic film should have suchcharacteristics that it can be etch processed under the etchingconditions to which the silicon-containing film is highly resistant, butit is highly resistant to the etching conditions under which theprocessable substrate is etch processed.

With respect to the organic film as the undercoat film, there are knowna number of films including undercoat films for the tri-layer resistprocess and undercoat films for the bi-layer resist process usingsilicon resist compositions. A number of resins including4,4′-(9H-fluoren-9-ylidene)bisphenol novolac resin with a molecularweight of 11,000 as described in JP-A 2005-128509 and other novolacresins are known as the resist undercoat film material for the bi- ortrilayer resist process, and any of them can be used herein. If it isdesired to enhance heat resistance beyond ordinary novolac resins, it ispossible to incorporate polycyclic skeletons as in4,4′-(9H-fluoren-9-ylidene)bisphenol novolac resins or to selectpolyimide resins (e.g., JP-A 2004-153125).

The organic film can be formed on a substrate from a compositionsolution by spin coating or similar techniques like the photoresistcomposition. After the resist undercoat film is formed by spin coatingor the like, it is desirably baked to evaporate off the organic solvent.The baking is preferably effected at a temperature of 80 to 300° C. fora time of 10 to 300 seconds.

Although the thickness of each film is not particularly limited andvaries depending on etching conditions, the undercoat film preferablyhas a thickness of at least 10 nm, and more preferably from 50 nm to50,000 nm, the silicon-containing film preferably has a thickness from 1nm to 200 nm, and the photoresist film preferably has a thickness from 1nm to 300 nm.

The tri-layer resist process using the silicon-containing film (foretching mask) according to the invention is described below. In theprocess, an organic film is first formed on a processable substrate byspin coating or similar techniques. This organic film is desired to havehigh etching resistance since it will serve as a mask during lateretching of the processable substrate, and is also desired to becrosslinked by heat or acid after spin coating since it should beprevented from intermixing with an overlying silicon-containing film(for etching mask). On the organic film, a silicon-containing film (foretching mask) of the inventive composition and a photoresist film areformed by the above-described technique. In accordance with the standardprocedure, the resist film is patternwise exposed to a light sourceselected for a particular resist film, for example, KrF excimer laser,ArF excimer laser or F₂ laser, heat treated under conditions selectedfor a particular resist film, and developed with a liquid developer,obtaining a resist pattern. While the resist pattern is made an etchingmask, etching is carried out under dry etching conditions under whichthe etching rate of the silicon-containing film is dominantly highrelative to the organic film, for example, dry etching with a fluorinegas plasma. When the ARC and the silicon-containing film are etchprocessed in this way, a pattern of the silicon-containing film isobtained without the substantial influence of pattern changes by sideetching of the resist film. Then, the undercoat organic film is etchedunder dry etching conditions under which the etching rate of theundercoat organic film is dominantly high relative to the substrate(having the silicon-containing film pattern to which the resist patternhas been transferred as described above), for example, by reactive dryetching with an oxygen-containing gas plasma or reactive dry etchingwith a hydrogen/nitrogen-containing gas plasma. This etching stepproduces a pattern of the undercoat organic film while the resist layeras the uppermost layer is often lost at the same time. Further, whilethe thus patterned undercoat organic film is made an etching mask, theprocessable substrate is processed by dry etching, for example, fluorinedry etching or chlorine dry etching. The processable substrate can beetch processed at a high accuracy.

EXAMPLE

Synthesis Examples and Examples are given below together withComparative Examples for further illustrating the invention although theinvention is not limited thereby.

Synthesis Example 1

A 1,000-ml glass flask was charged with 200 g of methanol, 200 g ofdeionized water, and 1 g of 35% hydrochloric acid. A mixture of 50 g oftetraethoxysilane, 100 g of methyltrimethoxysilane, and 10 g ofphenyltrimethoxysilane was added thereto at room temperature. The flaskwas held at room temperature for 8 hours while hydrolytic condensationtook place. To the reaction mixture, 300 ml of propylene glycolmonoethyl ether was added. Concentration under a reduced pressureyielded 300 g of a propylene glycol monoethyl ether solution ofsilicon-containing compound #1 (polymer concentration 21%). The polymerhad a weight average molecular weight (Mw) of 2,000 as measured versuspolystyrene standards.

Synthesis Example 2

Synthesis was carried out as in Synthesis Example 1 except that amixture of 100 g of methyltrimethoxysilane and 20 g ofphenyltrimethoxysilane was used instead of the mixture of 50 g oftetraethoxysilane, 100 g of methyltrimethoxysilane, and 10 g ofphenyltrimethoxysilane in Synthesis Example 1. There was obtained 300 gof a propylene glycol monoethyl ether solution of silicon-containingcompound #2 (polymer concentration 19%). The polymer had a Mw of 3,000as measured versus polystyrene standards.

Synthesis Example 3

Synthesis was carried out as in Synthesis Example 1 except that 260 g ofdeionized water, 5 g of 65% nitric acid, 70 g of tetramethoxysilane, 70g of methyltrimethoxysilane, 10 g of phenyltrimethoxysilane, and butanediol monomethyl ether were used instead of 60 g of methanol, 200 g ofdeionized water, 1 g of 35% hydrochloric acid, 50 g oftetraethoxysilane, 100 g of methyltrimethoxysilane, 10 g ofphenyltrimethoxysilane, and propylene glycol monoethyl ether. There wasobtained 300 g of a butane diol monomethyl ether solution ofsilicon-containing compound #3 (polymer concentration 20%). The polymerhad a Mw of 2,500 as measured versus polystyrene standards.

Synthesis Example 4

A 1,000-ml glass flask was charged with 260 g of deionized water and 1 gof 35% hydrochloric acid. A mixture of 70 g of tetramethoxysilane, 25 gof methyltrimethoxysilane, 25 g of a silane compound of formula (i),shown below, and 10 g of phenyltrimethoxysilane was added thereto atroom temperature. The flask was held at room temperature for 8 hourswhile hydrolytic condensation took place. Then the by-product methanolwere distilled off under a reduced pressure. To the reaction mixture,800 ml of ethyl acetate and 300 ml of propylene glycol monopropyl etherwere added. The water layer was separated off. To the remaining organiclayer, 100 ml of deionized water was added, followed by agitation,static holding and separation. This operation was repeated three times.To the remaining organic layer, 200 ml of propylene glycol monopropylether was added. Concentration under a reduced pressure yielded 300 g ofa propylene glycol monopropyl ether solution of silicon-containingcompound #4 (polymer concentration 20%). The solution was analyzed forchloride ions by ion chromatography, but no chloride ions were detected.The polymer had a Mw of 1,800 as measured versus polystyrene standards.

Synthesis Example 5

A 1,000-ml glass flask was charged with 200 g of ethanol, 100 g ofdeionized water and 3 g of methanesulfonic acid. A mixture of 40 g oftetramethoxysilane, 10 g of methyltrimethoxysilane, 50 g of a silanecompound of formula (ii), shown below, and 10 g ofphenyltrimethoxysilane was added thereto at room temperature. The flaskwas held at room temperature for 8 hours while hydrolytic condensationtook place. Then the by-product methanol were distilled off under areduced pressure. To the reaction mixture, 800 ml of ethyl acetate and300 ml of ethylene glycol monopropyl ether were added. The water layerwas separated off. To the remaining organic layer, 100 ml of deionizedwater was added, followed by agitation, static holding and separation.This operation was repeated three times. To the remaining organic layer,200 ml of ethylene glycol monopropyl ether was added. Concentrationunder a reduced pressure yielded 300 g of an ethylene glycol monopropylether solution of silicon-containing compound #5 (polymer concentration20%). The solution was analyzed for methanesulfonate ions by ionchromatography, finding that 99% of the catalyst used in reaction hadbeen removed. The polymer had a Mw of 2,100 as measured versuspolystyrene standards.

Examples and Comparative Examples

Silicon-containing film-forming composition solutions were prepared bydissolving silicon-containing compounds (#1 to #5), acid, thermalcrosslink accelerator, and additive in a solvent according to theformulation shown in Table 1, and passing through a fluoroplastic filterhaving a pore size of 0.1 μm. These solutions are designated Sol. 1 to10.

TABLE 1 Si-containing film-forming composition Si- Thermal containingcrosslink Water/ Other compound accelerator Acid Solvent stabilizeradditive No. (pbw) (pbw) (pbw) (pbw) (pbw) (pbw) Example 1 Sol. 1 #1TPSOAc maleic propylene water (10) — (4.0) (0.04) acid glycol Stabilizer1 (0.04) monoethyl (5) ether (100) 2 Sol. 2 #2 TPSOH oxalic propylenewater (5) — (4.0) (0.04) acid glycol Stabilizer 2 (0.02) monoethyl (5)ether (100) 3 Sol. 3 #3 TPSCl maleic butane water (5) — (4.0) (0.04)acid diol Stabilizer 3 TMAOAc (0.01) monomethyl (5) (0.003) ether (100)4 Sol. 4 #4 TPSMA maleic acid propylene water (5) — (4.0) (0.04) (0.01)glycol Stabilizer 4 TMAOAc oxalic acid monopropyl (5) (0.003) (0.01)ether (100) 5 Sol. 5 #5 TPSN maleic acid ethylene water (5) — (4.0)(0.04) (0.01) glycol Stabilizer 5 oxalic acid monopropyl (5) (0.01)ether (100) 6 Sol. 6 #1 TPSMA maleic acid propylene water (3) TPSNf(4.0) (0.04) (0.01) glycol Stabilizer 1 (0.02) monoethyl (5) ether (100)7 Sol. 7 #1 TPSOAc maleic acid propylene water (0) — (4.0) (0.04) (0.01)glycol Stabilizer 1 monoethyl (5) ether (100) Comparative Example 1 Sol.8 #1 TPSOAc — propylene water (5) — (4.0) (0.04) glycol Stabilizer 1monoethyl (5) ether (100) 2 Sol. 9 #1 — maleic acid propylene water (5)— (4.0) (0.01) glycol Stabilizer 1 monoethyl (5) ether (100) 3 Sol. 10#1 TPSOAc maleic acid propylene water (5) — (4.0) (0.04) (0.01) glycolStabilizer 1 monopropyl (0) ether (100) TPSOAc: triphenylsulfoniumacetate (photo-degradable thermal crosslink accelerator) TPSOH:triphenylsulfonium hydroxide (photo-degradable thermal crosslinkaccelerator) TPSCl: triphenylsulfonium chloride (photo-degradablethermal crosslink accelerator) TPSMA: mono(triphenylsulfonium) maleate(photo-degradable thermal crosslink accelerator) TPSN:triphenylsulfonium nitrate (photo-degradable thermal crosslinkaccelerator) TMAOAc: tetramethylammonium acetate (non-photo-degradablethermal crosslink accelerator) TPSNf: triphenylsulfoniumnonafluorobutanesulfonate (photoacid generator) Stabilizer 1:

Stabilizer 2:

Stabilizer 3:

Stabilizer 4:

Stabilizer 5:

First, an undercoat-forming material, specifically a compositioncontaining 28 parts by weight of a 4,4′-(9H-fluoren-9-ylidene)bisphenolnovolac resin with a molecular weight of 11,000 and 100 parts by weightof a solvent (see JP-A 2005-128509) was spin coated onto a silicon waferand baked at 200° C. for one minute to form an undercoat organic film of300 nm thick. While a number of resins including the above-specifiedresin and other novolac resins are known as the undercoat organic filmmaterial for the multilayer resist process, any of them can be usedherein.

Next, each of the silicon-containing film forming solutions (Sol. 1 to10) was spin coated and baked at 200° C. for 1 minute to form anSi-containing film of 100 nm thick.

Further, to form an overcoat resist film, a resist composition for ArFexcimer laser lithography (designated Resist 1) was prepared bydissolving 10 parts by weight of a resin, identified below, 0.2 part byweight of triphenylsulfonium nonafluorobutanesulfonate as a photoacidgenerator and 0.02 part by weight of triethanolamine as a basic compoundin propylene glycol monomethyl ether acetate (PGMEA) containing 0.1 wt %of Fluorad FC-430 (3M-Sumitomo Co., Ltd.) and passing through afluoroplastic filter having a pore size of 0.1 μm.

The resist composition was coated onto the Si-containing intermediatefilm and baked at 130° C. for 60 seconds to form a photoresist layer of200 nm thick.

Thereafter, the resist layer was exposed using an ArF laser stepperS305B (Nikon Corporation, NA 0.68, σ0.85, ⅔ annular illumination, Crmask), then baked (PEB) at 110° C. for 90 seconds, and developed with a2.38 wt % aqueous solution of tetramethylammonium hydroxide (TMAH),thereby giving a positive pattern. The profile of the 90 nmline-and-space pattern was observed, with the results shown in Table 2.

TABLE 2 Pattern profile No. Pattern profile Example 1 Sol. 1 good 2 Sol.2 good 3 Sol. 3 good 4 Sol. 4 good 5 Sol. 5 good 6 Sol. 6 good 7 Sol. 7good Comparative Example 1 Sol. 8 footing 2 Sol. 9 negative profile 3Sol. 10 good

In all Examples, the patterns were found to be free ofsubstrate-proximate footing, undercut and intermixing phenomena.

Next, dry etching resistance was tested. Each of the silicon-containingfilm forming solutions (Sol. 1 to 10) was spin coated and baked at 200°C. for 1 minute to form an Si-containing film of 100 nm thick (Film 1 to10). An etching test was performed on these films, the undercoat film,and the photoresist film under the following set of etching conditions(1). The results are shown in Table 3.

(1) CHF₃/CF₄ gas etching test Instrument: dry etching instrumentTE-8500P by Tokyo Electron Ltd. Chamber pressure: 40.0 Pa RF power:1,300 W Gap: 9 mm CHF₃ gas flow rate: 30 ml/mm CF₄ gas flow rate: 30ml/mm Ar gas flow rate: 100 ml/mm Treating time: 10 sec

TABLE 3 CHF₃/CF₄ gas dry etching rate Si-containing Si- CHF₃/CF₄ gas dryfilm-forming containing etching rate composition film (nm/min) Example 1Sol. 1 Film 1 400 2 Sol. 2 Film 2 500 3 Sol. 3 Film 3 450 4 Sol. 4 Film4 250 5 Sol. 5 Film 5 200 6 Sol. 6 Film 6 500 7 Sol. 7 Film 7 400Comparative 1 Sol. 8 Film 8 400 Example 2 Sol. 9 Film 9 400 3 Sol. 10Film 10 400 Resist film — — 120 Undercoat film — — 85

Separately, a rate of O₂ gas dry etching was examined under thefollowing set of etching conditions (2). The results are shown in Table4.

(2) O₂ gas etching test Chamber pressure: 60.0 Pa RF power: 600 W Ar gasflow rate 40 ml/min O₂ gas flow rate: 60 ml/min Gap: 9 mm Treating time:20 sec

TABLE 4 O₂ gas dry etching rate Si-containing film O₂ gas etching rate(nm/min) Example 1 Flim 1 2 2 Film 2 1 3 Film 3 2 4 Film 4 10 5 Film 515 6 Film 6 2 7 Film 7 2 Comparative 1 Film 8 2 Example 2 Film 9 2 3Film 10 2 Resist film — 250 Undercoat film — 210

It is seen that as compared with the undercoat film and the overcoatresist film, the silicon-containing intermediate films have a lowetching rate sufficient to use them as an etching mask in transferringthe pattern to the underlying layer.

Furthermore, a shelf stability test was performed. Thesilicon-containing film forming compositions (Sol. 1 to 10) preparedabove were stored at 30° C. for 3 months, following which they werecoated by the above-mentioned technique. It was examined whether anychange of film formation occurred before and after the storage. Theresults are shown in Table 5.

TABLE 5 Shelf stability test Composition State as coated Example 1 Sol.1 no thickness change, no pattern profile change 2 Sol. 2 no thicknesschange, no pattern profile change 3 Sol. 3 no thickness change, nopattern profile change 4 Sol. 4 no thickness change, no pattern profilechange 5 Sol. 5 no thickness change, no pattern profile change 6 Sol. 6no thickness change, no pattern profile change 7 Sol. 7 no thicknesschange, no pattern profile change Comparative 1 Sol. 8 5% thicknessincrease, pattern stripped Example 2 Sol. 9 no thickness change, patternstripped 3 Sol. 10 15% thickness increase, pattern stripped

It is seen from Table 5 that all the compositions of Examples remainstable at 30° C. over 3 months, corresponding to shelf stability at roomtemperature over 6 months.

The composition of the invention and the silicon-containing film thereofare improved in stability and lithographic characteristics. Theinventive composition enables pattern formation using thestate-of-the-art high-NA exposure system and substrate processing byetching.

Japanese Patent Application Nos. 2007-175956 and 2007-245832 areincorporated herein by reference.

Although some preferred embodiments have been described, manymodifications and variations may be made thereto in light of the aboveteachings. It is therefore to be understood that the invention may bepracticed otherwise than as specifically described without departingfrom the scope of the appended claims.

1. A heat curable silicon-containing film-forming composition comprising(A) a silicon-containing compound obtained through hydrolyticcondensation of a hydrolyzable silicon compound in the presence of anacid catalyst, (B) at least one compound having the general formula (1)or (2):L_(a)H_(b)X   (1) wherein L is lithium, sodium, potassium, rubidium orcesium, X is a hydroxyl group or a mono or polyfunctional organic acidresidue of 1 to 30 carbon atoms, “a” is an integer of at least 1, “b” is0 or an integer of at least 1, and a+b is equal to the valence ofhydroxyl group or organic acid residue,M_(a)H_(b)A   (2) wherein M is sulfonium, iodonium or ammonium, A is Xor a non-nucleophilic counter ion, “a” and “b” are as defined above, anda+b is equal to the valence of hydroxyl group, organic acid residue ornon-nucleophilic counter ion, (C) a mono or polyfunctional organic acidof 1 to 30 carbon atoms, (D) a mono or polyhydric alcohol substitutedwith a cyclic ether, and (E) an organic solvent.
 2. Thesilicon-containing film-forming composition of claim 1, wherein thesilicon-containing compound (A) comprises a silicon-containing compoundobtained by effecting hydrolytic condensation of a hydrolyzable siliconcompound in the presence of an acid catalyst which is selected frommineral acids, sulfonic acid derivatives and mixtures thereof to form areaction mixture containing the silicon-containing compound, andsubstantially removing the acid catalyst from the reaction mixture. 3.The silicon-containing film-forming composition of claim 1, wherein M informula (2) is tertiary sulfonium, secondary iodonium, or quaternaryammonium.
 4. The silicon-containing film-forming composition of claim 1,wherein M in formula (2) is photo-degradable.
 5. The silicon-containingfilm-forming composition of claim 1, further comprising water.
 6. Thesilicon-containing film-forming composition of claim 1, furthercomprising a photoacid generator.
 7. A silicon-containing film for usein a multilayer resist process involving the steps of forming an organicfilm on a processable substrate, forming a silicon-containing filmthereon, further forming a resist film thereon from a silicon-freechemically amplified resist composition, patterning the resist film,patterning the silicon-containing film using the resist film pattern,patterning the underlying organic film with the silicon-containing filmpattern made an etching mask, and etching the processable substrate withthe patterned organic film made an etching mask, the silicon-containingfilm being formed from the composition of claim
 1. 8. Thesilicon-containing film formed from the composition of claim 1, saidsilicon-containing film being used in the multilayer resist process ofclaim 7 wherein the process further involves the step of disposing anorganic antireflective coating between the resist film and thesilicon-containing film.
 9. A substrate having formed thereon, insequence, an organic film, a silicon-containing film of the compositionof claim 1, and a photoresist film.
 10. A substrate having formedthereon, in sequence, an organic film, a silicon-containing film of thecomposition of claim 1, an antireflective coating, and a photoresistfilm.
 11. The substrate of claim 9, wherein said organic film is a filmhaving an aromatic framework.
 12. A method for forming a pattern in asubstrate, comprising the steps of: providing the substrate of claim 9,exposing a pattern circuit region of the photoresist film to radiation,developing the photoresist film with a developer to form a resistpattern, dry etching the silicon-containing film with the resist patternmade an etching mask, etching the organic film with the patternedsilicon-containing film made an etching mask, and etching the substratewith the patterned organic film made an etching mask, for forming apattern in the substrate.
 13. A method for forming a pattern in asubstrate, comprising the steps of: providing the substrate of claim 10,exposing a pattern circuit region of the photoresist film to radiation,developing the photoresist film with a developer to form a resistpattern, dry etching the antireflective coating and thesilicon-containing film with the resist pattern made an etching mask,etching the organic film with the patterned silicon-containing film madean etching mask, and etching the substrate with the patterned organicfilm made an etching mask, for forming a pattern in the substrate. 14.The patterning method of claim 12, wherein said organic film is a filmhaving an aromatic framework.
 15. The patterning method of claim 12,wherein the exposing step is carried out by photolithography usingradiation having a wavelength equal to or less than 300 nm.